It is narrated in Tafsir of Imam Hasan Askari(as) regarding words of Allah(swt):
“Those who believe in the unseen……………” (Sura Baqara, Verse 3)
Imam Hasan Askari (a.s.) said: Almighty Allah, here, describes the virtue of those for whom this Book is a guide and says: ‘Those who believe in the unseen’, meaning they are the righteous people who believe in the unseen, that is, in those things which are hidden from eyes but which must, as per the divine command, be believed, such as rising after death and giving account of deeds and Paradise and Hell and Oneness of God which can be understood only through the signs which God has created, such as Adam, Hawwa, Idrees, Nuh, Ibrahim and all those messengers, belief in whom God has ordained through divine evidences, without seeing with eyes. They believe in such hidden things and fear Judgment Day.
Once Salman Farsi (r.a.) passed by a group of Jews. They requested Salman (r.a.) to sit near them and relate whatever he heard from Muhammad (s.a.w.s.). Longing for their becoming Muslims, Salman (r.a.) sat before them and said: Today, I heard from Muhammad (s.a.w.s.) that the Lord of the world says: O My servants! Does it not so happen that someone wants something from you but you do not intend to fulfill that need, but when he brings to you a person who is very friendly with You and who recommends his case, you fulfill the need? O My servants beware and know that My Messenger, Muhammad (s.a.w.s.) and his brother Ali (a.s.) and thereafter his truthful Imams (a.s.) are the means of approaching Me from the entire creation and they are most honorable in My sight. So, whoever has a need or whoever wants to be protected from any harm, should request Me in the name of Muhammad (s.a.w.s.) and his pious progeny. I will fulfill his need in the best way.
Hearing this, the Jews mockingly told Salman (r.a.): O Abu Abdullah! Then why do you not give the mediation of those persons and request God to make you the richest and wealthiest person in Medina? Salman (r.a.) replied: I have requested Almighty Allah to grant me a thing greater than the kingship of the whole world and which is most beneficial and it is that He may grant me a tongue which may continue praising Him and give me a heart which may constantly thank Him and also a mind that may value His bounties and that I may be patient during hardships. Almighty Allah has answered my appeal and granted that, which is more valuable than everything in the world.
The Jews laughed at Salman (r.a.) and told him: You have indeed asked for a very great rank from your Lord. Now we want to test the truthfulness of your intention. Just see, we are hitting you with this whip. Request your Lord to stop our hands from hitting you. Salman (r.a.) supplicated: O Lord! Grant me patience and forbearance in this calamity. The Jews began to hit Salman (r.a.) with their whips so much, that they became tired, but Salman (r.a.) said nothing except, O Lord! Grant me patience. When the cursed ones got extremely tired, they said: O Salman! We never imagined that anyone could remain alive after such whipping. We wonder why you did not ask your Lord to prevent us from giving you so much pain?! Salman (r.a.) replied: Such request would be against patience. Rather, I am pleased with the respite given by God to you. I have requested Him to grant me forbearance.
After a while, the Jews once again took up their whips and advanced towards Salman (r.a.) saying: Now we will continue hitting you, till the time you either die or deny the messengership of Muhammad (s.a.w.s.). Salman (r.a.) replied: I can never do the latter, I can never deny the messengership of Muhammad (s.a.w.s.) because Almighty Allah has revealed this verse to Muhammad (s.a.w.s.) in His Holy Quran: ‘Those who believe in the unseen’. Hence your oppression is easier for me to bear, so that God may admit me to the group which has been praised in this verse. Hearing this, the cursed ones hit Salman (r.a.) till their hands could move no more. So they sat down and said: O Salman! Had God raised your rank because of your belief in Muhammad (s.a.w.s.) He would have answered your supplication and prevented us from hitting you. Salman (r.a.) said: You are extremely ignorant. How could the Most Mighty Lord accept the request quoted by you? Had He accepted it, it would have been against my desire. I appealed Him to grant me patience and He accepted my request. I never asked Him to prevent you from oppressing me. Had it been so, it would have been against my desire. Your imagination is quite wrong.
Thereafter they started hitting Salman (r.a.) for the third time. But Salman (r.a.) continued to recite the same supplication, that is, O Allah! Grant me patience to bear this oppression due to my love for Your selected friend, Muhammad (s.a.w.s.). Then the Jews said: Woe unto you. Did Muhammad not allow you to speak something against your belief by way of dissimulation during such hard times? Salman (r.a.) replied: Indeed God has given me such permission, but it is not obligatory. It is permitted that I may not allow you to fulfill your evil intentions and continue to bear this oppression, as it is better and more honourable in my sight.
Hearing this, the cursed ones once again took up their whips and hit him so much that blood oozed out from his body. Then laughing more, they said: Why do you not request your God to prevent us from hitting you so that you may not have to speak what we want. If you are true in your faith, God will not reject your supplication. So request Him, giving mediation of Muhammad and his progeny, to destroy us. Salman (r.a.) replied: I regard it bad to ask for your destruction, because perhaps there may be someone among you about whom God knows that he would believe after some time. If I do as you say, it would mean that I asked for preventing that man from becoming faithful. After hearing this reply, the unfortunate and cursed ones said: Request God to destroy that man about whom He knows that he would not refrain from his high-handedness and rebellious haughtiness. In this way, you will be saved from what you fear.
Finally, when the Jews said so, a wall of the house in which they and Salman (r.a.) were present tore apart and Salman (r.a.) could see the Holy Prophet (s.a.w.s.) and hear him saying: O Salman! Pray for the destruction of this community as none from them is ever going to come to the true path. It is just like the time when Prophet Nuh (a.s.) knew, after final investigation, that none from his community except those who put faith, would believe, he prayed to God for their destruction. Then Salman (r.a.) asked the Jews what kind of divine punishment they would like. They replied: Ask your God so that He may turn all of these whips into pythons and every python may attack its owner and chew away his bones. Salman (r.a.) prayed accordingly.
Consequently, Allah Almighty turned every whip into a big snake having two heads. Every snake held the head of its holder in one mouth and with another mouth held the owner’s right hand that held the whip. Then the giant snakes broke and chewed their bones and finally swallowed them all. At that time, the Holy Prophet (s.a.w.s.) addressed his audience and said: O group of believers! Almighty Allah has helped your brother-in-faith, Salman (r.a.) against twenty Jews and hypocrites. Come, let us go and see the snakes which broke the oppressors bones and swallowed them up, the snakes that have been appointed by Allah to protect Salman (r.a.).
When the Holy Prophet (s.a.w.s.) and his companions reached the house in which Salman (r.a.) was oppressed, the snakes were killing the oppressors and the latter were screaming loudly. Hearing their screams, the Jews and hypocrites in neighborhood also had arrived there to see what was happening. But they could not go near them for fear of the deadly pythons. When the Holy Prophet (s.a.w.s.) reached there, all of them came out of that house and gathered in the street which was too narrow to accommodate all of them. But Almighty Allah due to the bounty of the holy steps of the Holy Prophet (s.a.w.s.) widened that street ten times.
When the snakes saw the Holy Prophet (s.a.w.s.), they jointly spoke out in pure language: Peace be on you, O Muhammad! O the leader of the formers and latters. Thereafter, they saluted Amirul Momineen (a.s.): Peace be on you, O Ali, the leader of the legatees. Thereafter, saluting the purified progeny of the Holy Prophet (s.a.w.s.) they said: Peace be on your Pure and Pious progeny whom Allah has made the establisher of the affairs of the entire creation. May our salute reach them. We are the whips of the hypocrites. Allah has turned us into snakes due to the prayer of this faithful, Salman (r.a.). Then the Holy Prophet (s.a.w.s.) said: All praise befits Allah who brought this servant of His in my community. He, initially due to refraining from cursing and continuing forbearance and finally cursing the oppressors after getting totally disappointed, is like Prophet Nuh (a.s.).
Then the pythons said: O Allah’s Messenger! We are extremely furious against these denier infidels. In the Kingdom of God, your and your legatee’s orders are binding on us. We wish that you pray to God that He may turn us into those giant snakes of Hell who may override these infidels, whereby like here in this world, we may continue to crush them in the Hereafter. The Holy Prophet (s.a.w.s.) replied: Your request has been accepted by God. Now throw out the pieces of the bodies of these oppressors out of your bellies and then go away into the lowest part of Hell so these oppressors may be more disgraced and that their disrepute may last longer. When they will be buried in the burial ground of Muslims, many believers will take lesson by looking at their graves knowing that they were destroyed due to the curse of a great friend of Muhammad (s.a.w.s.), that is, Salman (r.a.). Accordingly the snakes threw out the oppressors’ parts out of their mouths. Their relatives collected them and buried them.
Many disbelievers became faithful and many hypocrites turned into true believers. Also many infidels turned more stone-hearted and said: This is clear magic. The Holy Prophet (s.a.w.s.) turned towards Salman (r.a.) and said: O Abu Abdullah! You are our special faithful brother. God’s special angels love you from their hearts. In their sight, your excellence is higher than that of the sun over all from down in earth upto high heavens when there is nothing like darkness all around with no sign of any cloud. You are greater than all who have been praised by God in the verse: ‘Those who believe in the unseen’.
Source: Tafseer of Imam Hasan Askari(as), Sura Baqara, Verse 3