Sayyiduna Ibn Abbas (may Allah be pleased with them both) said that the Messenger of Allah (peace and blessings be upon him) said: "There is no one who has done me a greater favour than Abu Bakr (may Allah be pleased with him); he supported me with his own self and his wealth, and he gave me his daughter in marriage."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 11413