Musnad Abu Ya'la al-Mawsili 155:45

On the authority of Abu Hurairah, that Umar passed by Hassan while he was reciting poetry in the mosque, so he cast a glance at him. He (Hassan) said, "I used to recite in it, and in it was one who is better than you." Then he turned to Abu Hurairah and said, "I adjure you by Allah, did you hear the Messenger of Allah, may Allah bless him and grant him peace, say: 'Answer on my behalf; O Allah, support him with the Holy Spirit'?" He (Abu Hurairah) said, "O Allah, yes."