What teachings did Prophet Muhammad (peace be upon him) once share with Abu Huraira while he was in a state of fatigue and severe hunger?
      Narrated Abu Huraira:                          Once while I was in a state of fatigue (because of severe hunger), I      met 'Umar bin Al-Khattab, so I asked him to recite a verse from      Allah's Book to me. He entered his house and interpreted it to me.      (Then I went out and) after walking for a short distance, I fell on my     face because of fatigue and severe hunger. Suddenly I saw Allah's      Apostle  standing by my head. He said, "O Abu Huraira!" I replied,      "Labbaik, O Allah's Apostle, and Sadaik!" Then he held me by the hand,     and made me get up. Then he came to know what I was suffering from. He     took me to his house, and ordered a big bowl of milk for me. I drank      thereof and he said, "Drink more, O Abu Hirr!" So I drank again,      whereupon he again said, "Drink more." So I drank more till my belly      became full and looked like a bowl. Afterwards I met 'Umar and      mentioned to him what had happened to me, and said to him, "Somebody,      who had more right than you, O 'Umar, took over the case. By Allah, I      asked you to recite a Verse to me while I knew it better than you." On     that Umar said to me, "By Allah, if I admitted and entertained you, it     would have been dearer to me than having nice red camels.