Sahih Al Bukhari Hadith Number 906

Narrated Anas bin Malik: The Prophet (peace be upon him) used to offer the prayer earlier if it was very cold; and if it was very hot he used to delay the prayer, i.e. the Jumua prayer.

11  Friday Prayer
Hadith number 906
Volume no 2
Chapter: 17 (If it becomes very hot on Fridays)