Zayd bin Aslam narrates: I saw Sayyiduna Ibn Umar (may Allah be pleased with them both) praying with the buttons of his shirt undone. I asked him about it and he said: "I saw the Messenger of Allah (peace and blessings be upon him) doing this."
Only Zuhayr bin Muhammad narrated it. It reached me from Abu Isa al-Tirmidhi that he said: I asked Muhammad, meaning al-Bukhari, about this hadith of Zuhayr, and he said: I am wary of this shaykh; it is as though his hadith is fabricated (mawdu'), and in my view this is not Zuhayr bin Muhammad. Ahmad bin Hanbal used to declare this shaykh da'if (weak) and say: This is a shaykh whose name they must have turned around. Al-Bukhari pointed to some of this in al-Tarikh.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 3296
Hadith Gradingمحدثین:صحيح لغيره
Hadith Takhrij«صحيح لغيره۔ وله طريق آخر عند البخاري في تاريخ 8/ 174۔ وسنده ايضا ضعيف»