(a) Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) says that whenever one of you prostrates, he must place his nose on the ground, for you have been commanded to do so.
(b) Likewise Sharik narrated this from Simak; and it is also narrated from Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) that the Prophet (peace and blessings be upon him) said: "Place your nose on the ground so that your nose too prostrates along with you."
(c) Imam Abu Isa al-Tirmidhi (may Allah have mercy on him) says: The narration of Ikrimah from the Prophet (peace and blessings be upon him) in mursal form is more authentic.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 2656
Hadith Gradingمحدثین:حسن لغيره تقدم في الذي قبله زياده صحيح هي
Hadith Takhrij«حسن لغيره تقدم في الذي قبله زياده صحيح هي۔»