Sunan an Nasai
1311
Sahih Isnaad+2

It was narrated from Jabir that:The Messenger of Allah (ﷺ) used to say in his prayer, after the tashahhud: "The best of word is the word of Allah (SWT) and the best of guidance is the guidance of Muhammad (ﷺ)

Sahih IsnaadAbu Ghuddah
Sahih IsnaadAl-Albani