Muhammad bin Umar bin Ali bin Abi Talib (may Allah have mercy on him) says that on the day of the Camel Sayyiduna Ali (may Allah be pleased with him) said: "We show them favour because they bear witness to the testimony of tawhid, and we will make their fathers heirs of their children."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب قتال أهل البغي / 16751