Zirr bin Hubaysh narrates: One day the Messenger of Allah (peace and blessings be upon him) was leading the people in prayer when Hasan and Husayn (may Allah be pleased with them both) came, and they were both young boys. They climbed onto the back of the Messenger of Allah (peace and blessings be upon him) while he was in prostration. The people turned towards them to move them away from doing that. He (peace and blessings be upon him) said: "Leave them, may my father and mother be ransomed for them. Whoever loves me, let him love these two."
Imam al-Bayhaqi (may Allah have mercy on him) said: Sayyiduna Anas bin Malik (may Allah be pleased with him) said: I have not seen anyone more compassionate and kind towards children than the Messenger of Allah (peace and blessings be upon him).
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 3424