Story of a man who used to sit with drinkers; and who was Abu Thawr?

What you have mentioned is a strange story, which we have never heard of. But what we know and are certain of is that sitting with people who are drinking alcohol is haraam, because Allaah has forbidden the Muslims to sit in gatherings where evil things are happening. Allaah says (interpretation of the meaning):

 “And when you (Muhammad) see those who engage in a false conversation about Our Verses (of the Qur’aan) by mocking at them, stay away from them till they turn to another topic. And if Shaytaan (Satan) causes you to forget, then after the remembrance sit not you in the company of those people who are the Zaalimoon (polytheists and wrongdoers).

[al-An’aam 6:68]

 “And it has already been revealed to you in the Book (this Qur’aan) that when you hear the Verses of Allaah being denied and mocked at, then sit not with them, until they engage in a talk other than that; (but if you stayed with them) certainly in that case you would be like them. Surely, Allaah will collect the hypocrites and disbelievers all together in Hell.” [al-Nisaa’ 4:140]

 Some people who had been drinking wine were brought to ‘Umar ibn ‘Abd al-‘Azeez (may Allaah have mercy on him) and he commanded that they should be flogged. One of them offered the excuse that he had not actually been drinking, but ‘Umar commanded that he should be flogged along with the others, and he recited this aayah to him. And Allaah knows best.

 Concerning Abu Thawr, this is a brief glance at his biography:

 His name was Ibraaheem ibn Khaalid. His kunyas (agnomen, nicknames) were Abu ‘Abd-Allaah and Abu Thawr, and he is best known by the latter.

 He was born in Haroor in 170 AH. He was one of the fuqahaa’ of Iraq, and one of the scholars of hadeeth. Imaam Ahmad praised him by saying, “I know that this man has been following the Sunnah – i.e., the correct belief – for fifty years.”

 He lived for seventy years or more, and died in 240 AH.