It was narrated that 'Abdullah bin Shaqiq said:
"I said to 'Aishah: 'Which of the (Prophet's) Companions was most beloved to him?' She said: 'Abu Bakr.' I said: 'Then which of them?' She said: ''Umar.' I said: 'Then which of them?' She said: 'Abu 'Ubaidah.'" (ID)
English reference (ID): Vol. 1, Book 1, Hadith 102 (ID)
Arabic reference (ID): Book 1, Hadith 107 (ID)