It is narrated from Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) that the Prophet (peace and blessings be upon him) said: "There is no hilf (mutual alliance pact) in Islam, and as for any hilf (pact) that existed in the Jahiliyyah, Islam has only added to its sharpness and strength."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 11690