A man asked the Prophet ﷺ about something concerning the prayer.The Messenger of Allah ﷺ said to him, "Run your fingers between the fingers of your hands and the toes of your feet," meaning, perform a thorough ablution.Among what he told him was, "When you bow, place your palms on your knees until you are still," (and al-Hashimi once said, "until they are still"), "and when you prostrate, press your forehead firmly against the ground until you feel the solidness of the earth."
سأل رجل النبي ﷺ عن شيء من أمر الصلاة؛ فقال له رسول الله ﷺ: خلل أصابع يديك ورجليك-يعني إسباغ الوضوء وكان فيما قال له: إذا ركعت فضع كفيك على ركبتيك حتى تطمئن، ( وقال الهاشمي مرة): حتى تطمئنا- وإذا سجدت فأمكن جبهتك من الأرض، حتى تجد حجم الأرض.
Imam Ahmad narrated it (2604), he said, Sulayman bin Dawud Hashimi told us, Abdul-Rahman bin Abu Zinad told us, from Musa bin Uqba, from Salih the freed slave of Tawama, who said, I heard Ibn Abbas say, then he related the hadith. Its chain is hasan because of Abdul-Rahman bin Abu Zinad, for there is disagreement about him, and Salih the freed slave of Tawama became confused in his later years, but Musa bin Uqba heard from him before that confusion set in. The takhrij of this hadith was given earlier in the book of wudu, in the chapter on running the fingers through the fingers and toes, for the first part of the hadith was narrated by Tirmidhi and Ibn Majah with this same chain.Hafiz said in Talkhis (1/94), "In it is Salih the freed slave of Tawama, who is daif, but Bukhari graded it hasan, because it comes through the narration of Musa bin Uqba from Salih, and Musa's hearing from him was before he became confused."