Sayyiduna Jarir (may Allah be pleased with him) said: the Prophet (peace and blessings be upon him) said: "The Muhajirun and the Ansar are allies of one another in this world and the Hereafter, and the Tulaqa' of Quraysh (those set free on the day of the Conquest of Makkah) and the 'Utaqa' of Thaqif (those set free) are also allies of one another in this world and the Hereafter."
Hadith Referenceالمعجم الكبير للطبراني / باب الجيم / 2271