With a child on each knee
Usāma sat on one thigh and Ḥasan on the other, and he ﷺ held them both.
اللَّهُمَّ ارْحَمْهُمَا فَإِنِّي أَرْحَمُهُمَا
Allāhumma-rḥamhumā fa-innī arḥamuhumā.
“O Allah, have mercy on them, for I am merciful to them.”
One was his grandson and one was the son of a freed slave, and he made no distinction between the two knees.
The full narration
Narrated Usama bin Zaid:Allah's Messenger (ﷺ) used to put me on (one of) his thighs and put Al-Hasan bin `Ali on his other thigh, and then embrace us and say, "O Allah! Please be Merciful to them, as I am merciful to them
Source
Ṣaḥīḥ al-Bukhārī · 6003
Ṣaḥīḥ
- Agreed upon as authentic (al-Bukhārī / Muslim)