al-Ḥasan al-Baṣri:
“We used to be amongst a group of people (i.e., the Companions) who would never do any act in public if they could do so in private.
And those Muslims would strive in making their du’aa, and not a sound would be heard from them!
For they used to whisper to their Lord.”
[Report by at-Tabari in his Tafsir 5/514]