Jami At Tirmidhi
2897
Sahih+3

Narrated Abu Hurairah:"I went out with the Messenger of Allah and heard a man reciting Qul Huwa Allahu Ahad [Allahus-Samad] so the Messenger of Allah (ﷺ) said: 'It is obligatory.' I said: 'What is obligatory?' He said: 'Paradise

SahihAhmad Muhammad Shakir
SahihAl-Albani