Qailah bint Makhramah (May Allah be pleased with her) reported:
I saw the Prophet (ﷺ) seated with his arms enfolding his legs; and when I saw him in such a state of humble guise I trembled with fear due to the awe (he showed in that posture).[At-Tirmidhi].
App reference: Book 5, Hadith 10
Arabic/English book reference: Book 5, Hadith 823