It is narrated from Hasan (may Allah have mercy on him), who narrates from his mother, that she said: I saw Umm Salamah (may Allah be pleased with her), the wife of the Prophet ﷺ, prostrating on a pillow made of leather.
Hadith Referenceمسند الإمام الشافعي / كتاب الصلاة / 244
Hadith Takhrijاسنادہ ضعیف: ام الحسن مقبولہ حیث تتابع ولم تتابع أخرجہ البہیقی: 307/2 وفی معرفۃ السنن والآثار لہ (1081)۔
It is narrated from Mujahid (may Allah have mercy on him) who states: A servant is closest to Allah while in the state of prostration. Have you not reflected on Allah’s saying: “Prostrate and draw near,” that is, prostrate and attain closeness to Allah.
Hadith Referenceمسند الإمام الشافعي / كتاب الصلاة / 245