The length of the Messenger of Allah's ﷺ shadow when he prayed in summer was between three and five feet, and in winter between five and seven feet.
كانت قدر صلاة رسول الله ﷺ في الصيف ثلاثة أقدام إلى خمسة أقدام، وفي الشتاء خمسة أقدام إلى سبعة أقدام.
Abu Dawud (400) and Nasai (503) both recorded it, both via the route of Ubayda bin Humayd, from Abu Malik Ashjai Saad bin Tariq, from Kathir bin Mudrik, from Aswad, that Abdullah bin Masud reported to him, and he mentioned the hadith. Its chain is hasan because of Ubayda bin Humayd Kufi, who is trustworthy (saduq), while the rest of the men are reliable (thiqat).His statement, "the length of the Messenger of Allah's prayer" ﷺ, means the extent of delaying the prayer past the sun's zenith. The hadith of Abdullah bin Masud serves as an explanation of ibrad, for the last time of Dhuhr prayer in the summer is between three feet and five feet of shadow, and delaying beyond this is not permissible. This is why Nasai titled his chapter, "The last time of Dhuhr." The measurements of shadow in feet, however, differ according to region and country, and are not the same across all cities and territories, as Khattabi stated.