It is narrated from Sayyida Aisha (may Allah be pleased with her) that when Sayyiduna Abu Bakr Siddiq (may Allah be pleased with him) was passing away, he recited this verse:

وَاَبْیَضَ یُسْتَسْقٰی الْغَمَامُ بِوَجْھِہٖ
رَبِیْعُ الْیَتَامٰی عِصْمَۃٌ لِلْاَ رَامِلٖ

And the fair one, by whose face rain is sought from the clouds,
He is the nurturer of orphans and the protector of widows.

Sayyiduna Abu Bakr (may Allah be pleased with him) said upon hearing this: By Allah! This person was indeed the Messenger of Allah (peace and blessings be upon him).