(a) It is narrated from Salih bin Haywan al-Saba'i (may Allah have mercy on him) that the Messenger of Allah (peace and blessings be upon him) saw a man prostrating beside him, who had his forehead covered (with his turban). He (peace and blessings be upon him) uncovered his forehead.
(b) It is narrated from Iyad bin Abdullah al-Qurashi (may Allah have mercy on him) that the Messenger of Allah (peace and blessings be upon him) saw a man prostrating on his turban, so he (peace and blessings be upon him) gestured with his hand, saying: "Push your turban back," and he pointed to his forehead.
This mursal report is a supporting witness (shahid) for the mursal report of Salih.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 2659