Ahmed bin Muhammed Al-Marroozi (rahimahullah) mentions, “I posed many questions to Imaam Ahmed (rahimahullah), the number of which I cannot remember, and he replied, ‘I do not know the answer.’”

Muhammed bin ‘Ubaid Al-Yamaami (rahimahullah) reports that he heard Imaam Ahmed (rahimahullah) mention, “In regard to certain masaa’il, I only arrived at a decision regarding the ruling after three years of contemplation.”

(Manaaqib Imaam Ahmed libnil Jowzi pg. 358-359)