The most excellent invocation is: Praise is for Allah. and the most excellent words of remembrance a...

Reference:At-Tirmidhi 5/462, Ibn Majah 2/1249, and Al-Hakim who graded it authentic and Ath-Tbahabi agreed 1/503. See Al-Albani, Sahihul-Jami' As-Saghir 1/362.Hisnul Muslim 264

إِنَّ أَفْضَلَ الدُّعَاءِ (الْحَمْدُ لِلَّهِ) وَأَفْضَلَ الذِّكْرِ (لاَ إِلَهَ إِلاَّ اللَّهُ)

Transliteration

The most excellent invocation is: Alḥamdulillāh and the most excellent words of remembrance are: Lā ilāha illallāh.

Translation

The most excellent invocation is: Praise is for Allah. and the most excellent words of remembrance are: There is none worthy of worship but Allah.