"Do not talk too much without remembrance of Allah. Indeed excessive talking without remembrance of Allah hardens the heart. And indeed the furthest of people from Allah is the harsh-hearted."
Jami` at-Tirmidhi Book 36, Hadith 109
← Previous Hadith I said: "O Messenger of Allah! Inform me about a matter that I may hold fast to." He said: 'Say: My Lord is Allah, then be steadfast.' I said: "O Messenger of Allah! What do you fear most for me?" So he took hold of his tongue and said: 'This.'"

Jami` at-Tirmidhi Book 36, Hadith 108 Next Hadith → "The son of Adam's speech is against him not for him, except for commanding good, or forbidding evil, or remembrance of Allah."

Jami` at-Tirmidhi Book 36, Hadith 110