Sahih al-Bukhari 3555
Sahih al-Bukhari · Book 61: Virtues and Merits of the Prophet (pbuh) and his Companions · The description of the Prophet (saws)
Narrated `Aisha:
حَدَّثَنَا يَحْيَى ، حَدَّثَنَا عَبْدُ الرَّزَّاقِ ، حَدَّثَنَا ابْنُ جُرَيْجٍ ، قَالَ أَخْبَرَنِي ابْنُ شِهَابٍ ، عَنْ عُرْوَةَ ، عَنْ عَائِشَةَ ـ رضى الله عنها ـ أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم دَخَلَ عَلَيْهَا مَسْرُورًا تَبْرُقُ أَسَارِيرُ وَجْهِهِ، فَقَالَ " أَلَمْ تَسْمَعِي مَا قَالَ الْمُدْلِجِيُّ لِزَيْدٍ وَأُسَامَةَ ـ وَرَأَى أَقْدَامَهُمَا ـ إِنَّ بَعْضَ هَذِهِ الأَقْدَامِ مِنْ بَعْضٍ " .
That Allah's Messenger (ﷺ) came to her in a happy mood with his features glittering with joy, and said, "Have you not heard what the Qaif has said about Zaid and Us-ama? He saw their feet and remarked. These belong to each other." (i.e. They are father and son.)