Silsilat al-Ahadith al-Sahihah

Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) narrates that the Messenger of Allah (peace and blessings be upon him) used to pray, and when he would go into prostration, Hasan and Husayn would jump and climb onto his back. When the companions intended to stop them, he (peace and blessings be upon him) would gesture to let them (remain as they were). When he completed the prayer, he would seat them in his lap and say: "Whoever loves me should love these two."