It was narrated that Hudhaifah bin Yaman said:
"The Messenger of Allah (ﷺ) said: 'I do not know how long I will stay among you, so follow the example of these two after I am gone,' and he pointed to Abu Bakr and `Umar." (ES)
English reference (ES): Vol. 1, Book 1, Hadith 97 (ES)
Arabic reference (ES): Book 1, Hadith 102 (ES)