Authentic Supplication Number 111.

It is reported of ‘Uqbata bin ‘Amir that he said: “The Messenger of Allah  ordered that I read The Mu`awwithat (135) after every salat”.

Footnotes.
(135) This is a reference to the last two suwar (called chapters in English) of the Qur’an.

Reporters.
Reported by Abu Dawood, At-Tirmithi, and An-Nisa’ee. Al-Albani said that it was also reported by Ahmad. He said it was of sound ascription, and that Ibn Hibban said it was sound. He included this hadeeth in The Authentic of Good Sayings as #94.