Fool's heart in mouth, wise man's tongue in heart
Nahj al-Balāgha|Volume 1|Book 3|Chapter 41
٤١. وقد روي عنه (عليه السلام) هذا المعنى بلفظ آخر، وهو قوله: قَلبُ الْأَحْمَقِ فِي فِيهِ، وَلِسَانُ الْعَاقِلِ فِي قَلْبِهِ.
41. This very sense has been related from Amīr al-mu’minīn, peace be upon him, in a different version as follows: The heart of a fool is in his mouth while the tongue of the wise man is in his heart.
ومعناهما واحد.
The meaning of both the sayings (40 and 41) is the same.