Ibn Umar reported: The Messenger of Allah, peace and blessings be upon him, said:

لَا تُكْثِرُوا الْكَلَامَ بِغَيْرِ ذِكْرِ اللَّهِ فَإِنَّ كَثْرَةَ الْكَلَامِ بِغَيْرِ ذِكْرِ اللَّهِ قَسْوَةٌ لِلْقَلْبِ وَإِنَّ أَبْعَدَ النَّاسِ مِنْ اللَّهِ الْقَلْبُ الْقَاسِي

Do not speak too much without remembering Allah. Verily, too much talking without remembering Allah hardens the heart. The furthest of people from Allah is one with a hard heart.

Source: Sunan al-Tirmidhī 2411, Grade: Hasan