How soothing it is to the heart..

وَذَكَرَ الشَّعْبِيُّ ، عَنْ عَلِيٍّ ، رَضِيَ اللَّهُ عَنْهُ أَنَّهُ خَرَجَ عَلَيْهِمْ وَهُوَ يَقُولُ : ” مَا أَبْرَدَهَا عَلَى الْكَبِدِ ، مَا أَبْرَدَهَا عَلَى الْكَبِدِ ” ، فَقِيلَ لَهُ : وَمَا ذَاكَ ؟ قَالَ : ” أَنْ تَقُولَ لِلشَّيْءِ لا تَعْلَمُهُ : اللَّهُ أَعْلَمُ

جامع بيان العلم و فضله

It was narrated from ash-Sha’bi that Ali (may God be pleased with him) went out to them saying:

“How soothing it is to the heart.” It was said to him: “What is that?” He said:

“To say, when you do not know something: God knows best.”

– Jami ‘Bayan al-‘Ilm wa Fadlihi 2/66