Abu Bakr kissed the Prophet ﷺ after he had died.
أخبرنا يعقوب بن إبراهيم ومحمد بن المثنى قالا حدثنا يحيى عن سفيان قال حدثني موسى بن أبي عائشة عن عبيد الله بن عبد الله
أن أبا بكر قبل النبي ﷺ وهو ميت
No references are available.
Bukhari transmitted it in the Book of Military Expeditions, chapter on the Prophet's ﷺ illness and death, hadith no. 4455, from the hadith of Yahya Qattan through this route, and it is also in Kubra, hadith no. 1966.