Sayyiduna Jundub (may Allah be pleased with him) narrates: I heard the Prophet Muhammad (peace and blessings be upon him) five days before his passing, delivering a sermon to the people, in which he said: "O people! There was brotherhood and friendship among you before, and I declare myself free before Allah from having taken any one of you as a close friend (khalil). If I were to take anyone from my Ummah as a close friend, I would have taken Abu Bakr as my close friend. Indeed, Allah Almighty has taken me as His close friend, just as He took Sayyiduna Ibrahim (peace be upon him) as His close friend. The people before you used to turn the graves of their prophets and righteous people into places of worship, so do not turn graves into mosques; I forbid you from this."