Is accompanying a friend who leads to a major sin a reason to abandon him forever, especially after repenting and staying away from the sin for four months, then returning to it because of him?

It is necessary to sever ties with a friend who leads one to commit sins. What helps in this regard is to stay away from places where they are present, seek good company, occupy one's time with beneficial activities such as seeking knowledge and memorizing the Quran, increase acts of obedience, and reflect on the consequences of associating with bad companions. Abandoning a sinful friend should be done according to what is beneficial, along with advising them and explaining the seriousness of their actions.