Shaykh Ṣālih Al-Fawzān (hafidahullāh):

The tongue is the most dangerous of limbs, due to this every limb frees themselves from the tongue, admonishes it and reminds it to fear Allāh and have taqwa of Him, by saying:

” Fear Allāh for our sake, (for) we are with you; if you are upright, we will be upright; and if you are crooked, we will become crooked.” [1]

Source: Official Website of the Shaykh

[1] [Reported by Tirmidhī Number 2407: Chapter: What has been reported concerning preservation of the tongue] [Hadīth Declared Hasan By Imām Albāni]