Explanation
The Prophet (may Allah's peace and blessings be upon him) was sitting with a group of his Companions, including Abu Bakr and ‘Umar. Then he (may Allah's peace and blessings be upon him) stood up and delayed returning. They feared that he might have encountered harm from an enemy, either by capturing or some other misfortune. The Companions (may Allah be pleased with them) stood up terrified, and the first to act was Abu Hurayrah (may Allah be pleased with him). He went to a garden belonging to Banu An-Najjār and started looking around, hoping to find an open gate, but he found none. However, he found a small opening in the wall through which water flowed. He squeezed his body through the opening and entered, where he found the Prophet (may Allah's peace and blessings be upon him), who said to him: Are you Abu Hurayrah? He said: Yes. He said: What is the matter with you? Abu Hurayrah said: You were among us, then you left and delayed returning, so we feared that you would be taken away from us. We became terrified, and I was the first to act. I came to this orchard and crouched down just as a fox crouches, and those people are behind me. The Prophet (may Allah's peace and blessings be upon him) gave him his sandals as a sign and proof of his truthfulness and said to him: Take these two sandals of mine and go. Whoever you meet beyond this orchard who bears witness that there is no god but Allah and that no deity is truly worthy of worship except Allah, with full certainty in his heart—whoever has these qualities is among the people of Paradise. The first person he met was ‘Umar, who asked him: What are these two sandals, O Abu Hurayrah? He replied: These are the sandals of the Messenger of Allah (may Allah's peace and blessings be upon him). He sent me with them to give the glad tidings of Paradise to anyone I meet who bears witness that there is no god but Allah, with full certainty in his heart. ‘Umar struck Abu Hurayrah on his chest, causing him to fall on his back, and he said: Go back, O Abu Hurayrah. So, I returned to the Prophet (may Allah's peace and blessings be upon him), alarmed, with my face changed and on the verge of weeping. ‘Umar followed behind me, walking after me. He (may Allah's peace and blessings be upon him) said: What is the matter, O Abu Hurayrah? I said: I met ‘Umar and told him about what you sent me with, so he struck me such a strike that caused me to fall on my back and said: Go back. He (may Allah's peace and blessings be upon him) said: O ‘Umar, what caused you to do that? ‘Umar said: O Messenger of Allah, may my father and mother be sacrificed for you! Did you send Abu Hurayrah with your sandals to give glad tidings of Paradise to anyone who bears witness that there is no god but Allah, with full certainty in his heart? He said: Yes. He said: Then do not do that, for I fear that people may rely only on saying this without acting upon it. Let them continue to work. He (may Allah's peace and blessings be upon him) said: Then let them.