Sunan Ibn Majah
682
Sahih+3

It was narrated from Anas bin Malik that:The Messenger of Allah used to pray 'Asr when the sun was still hot and high, and if a person were to go to the suburbs (of Al-Madinah) he would be able to reach it while the sun was still hot and high

SahihAl-Albani
SahihMuhammad Fouad Abd al-Baqi