Hisnul Muslim 252

Seeking forgiveness and repentance

وقال صلى الله عيه وسلم :" أقرب ما يكون العبد من ربه وهو ساجد فأكثروا الدعاء"

The Prophet (SAW) said: "The closest that the slave comes to his Lord is when he is prostrating, so invoke Allah much (in prostration)".