O Mu’adh! By Allah I love you, so I advise you to never forget to recite after every prayer

[AbdurRahman.Org]

وعن معاذ رضي الله عنه أن رسول الله صلى الله عليه وسلم أخذ بيده وقال‏:‏ ‏”‏يا معاذ والله إني لأحبك‏”‏ فقال‏:‏
“‏أوصيك يا معاذ لا تدعن في دبر كل صلاة تقول‏:‏
اللهم أعني على ذكرك، وشكرك، وحسن عبادتك‏“
[ رواه أبو داود بإسناد صحيح]

Mu’adh (رضي الله عنه) reported: The Messenger of Allah (صلى الله عليه وسلم) took hold of my hand and said, “O Mu’adh! By Allah I love you, so I advise you to never forget to recite after every prayer:

اللَّهُمَّ أَعِنِّي عَلَى ذِكْرِكَ، وَشُكْرِكَ، وَحُسْنِ عِبَادَتِكَ
“Allâhumma a’innî alâ dhikrika, wa shukrika, wa husni ‘ibâdatika 
O Allah, help me remember You, to be grateful to You, and to worship You in an excellent manner”

[Abu Dawud] [Book 16, Hadith 1422]
Source: Riyad as-Salihin » The Book of the Remembrance of Allah » 1422
Darussalam English Publication

https://authentic-dua.com/2018/08/17/allahumma-ainni-ala-dhikrika-wa-shukrika-wa-husni-ibadatika/