What is the ruling on befriending or following friends who do not pray and remember Allah only a little, or for the sake of oaths and vows?

Your duty towards those who live with you is to advise them and call them to righteousness with wisdom and gradualness, choosing the appropriate method and time, and seeking help from righteous people, beneficial books, and useful tapes. Be patient, emulating the prophets, and distinguish between your role in calling them to Islam and befriending them. Do not mix with them except out of necessity, with legitimate controls, if you fear deviation for yourself. Avoid arrogance and despising others, and look at yourself with an eye of shortcoming and at sinners with an eye of compassion.