Muhammad bin Sirin (may Allah have mercy on him) says: I was informed that when the Messenger of Allah (peace and blessings be upon him) prayed, he would raise his gaze towards the sky. Then a verse was revealed; if it was not "Those who humble themselves in their prayers" [Surah al-Mu'minun: 2], then I do not know which verse it was. Ibn Sirin (may Allah have mercy on him) liked that the gaze of one praying should not go beyond his place of prayer.
What is preserved is that it is mursal; it has also been narrated from Isma'il bin Ibrahim (Ibn Ulayyah) as a connected report.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 3541