It is narrated from Sayyiduna Abdullah bin Amr bin al-As (may Allah be pleased with them both) that the Messenger of Allah (peace and blessings be upon him) addressed the people on an extremely hot day, and he (peace and blessings be upon him) saw a man standing in the sun, as though he were a Bedouin. The Prophet (peace and blessings be upon him) asked him: "What is the matter, that I see you standing?" He said: "I have vowed that I will not sit down until you finish the sermon." So the Prophet (peace and blessings be upon him) said to him: "Sit down. This is not a vow; a vow is only that by which the pleasure of Allah, the Mighty and Majestic, is sought."
Imam al-Tabarani (may Allah have mercy on him) said: "No one narrated this hadith from Abu al-Zinad (may Allah have mercy on him) except his son, and no one from his son except Abdullah bin Nafi' (may Allah have mercy on him), while Muslim bin Amr (may Allah have mercy on him) is alone in narrating it."
Hadith Referenceالمعجم الأوسط / باب الألف / 1410
Hadith Gradingمحدثین:إسناده ضعيف لضعف عبد الله بن نافع المدني
Hadith Takhrij«قال الهيثمي: وفيه عبد الله بن نافع المدني وهو ضعيف «مجمع الزوائد ومنبع الفوائد، ج 4، ص 187»» «أخرجه أبو داود فى «سننه» برقم: 3273، والبيهقي فى «السنن الكبرى» برقم: 20149، والدارقطني فى «سننه» برقم: 4330، وأحمد فى «مسنده» برقم: 6847، 7095، والطحاوي فى «شرح معاني الآثار» برقم: 4831، والطحاوي فى «شرح مشكل الآثار» برقم: 4162»