He saw the Messenger of Allah ﷺ trim his hair with an arrow blade.I said to Ibn Abbas, "We have heard this matter only from Muawiya."He replied, "Muawiya was not one to be suspected of lying about the Messenger of Allah ﷺ."
حدثنا مروان بن شجاع قال حدثني خصيف عن مجاهد وعطاء عن ابن عباس أن
أنه رأى رسول الله ﷺ قصر من شعره بمشقص فقلت لابن عباس ما بلغنا هذا الأمر إلا عن معاوية فقال ما كان معاوية على رسول الله ﷺ متهما
Its isnad is sahih, it was already mentioned at 16837.16877m - Ibrahim bin Abdullah bin Bashar Wasiti told us, Muammal and Abu Ahmad, or one of the two, told us, from Sufyan, from Jafar bin Muhammad, from his father, from Ibn Abbas, from Muawiya, that the Prophet ﷺ shortened his prayer in Hims. Sahih.(16877m) Its isnad is sahih. Ibrahim bin Abdullah bin Bashar, or Bassar, Wasiti was deemed trustworthy by Khatib, while Abu Zura and Ibn Makula considered him unknown, but this was refuted in Taajil.