Full Sharh — Riyad as-Salihin 842
وعن أبي سعيد الخدري رضي الله عنه عن النبي صلى الله عليه وسلم قال: “إذا أصبح ابن آدم، فإن الأعضاء كلها تكفر اللسان، تقول: اتقِ الله فينا، فإنما نحن بك: فإن استقمت استقمنا وإن اعوججت اعوججنا”. ((رواه الترمذي)). 'معني “تكفر اللسان” أي تذل وتخضع له.
English Translation
Abu Sa'id Al-Khudri (May Allah be pleased with him) said:: The Prophet (ﷺ) said, "When the son of Adam gets up in the morning, all the limbs humble themselves before the tongue and say: 'Fear Allah for our sake because we are with you: (i.e., we will be rewarded or punished as a result of what you do) if you are straight, we will be straight; and if you are crooked, we will become crooked."'.
Source
Riyad as-Salihin(رياض الصالحين)
The Book of the Prohibited actions
Hadith Number
842