Maliks Muwatta Book 9, Hadith Number 55.
Section : Waiting for The Prayer and Walking to It.
Yahya related to me from Malik from Abu’z Zinad from al-Araj from Abu Hurayra that the Messenger of Allah, may Allah bless him and grant him peace, said, “You are in prayer as long as the prayer detains you and there is nothing that prevents you from returning to your family except the prayer.”