Sunan an Nasai
1149
Sahih+2

It was narrated that Abdullah said:"The Messenger of Allah (ﷺ) used to say the takbir every time he got up, went down, stood and sat. Abu Bakr, 'Umar, and 'Uthman (did likewise)

SahihAbu Ghuddah
SahihAl-Albani