Masruq narrates: Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) prayed as soon as the sun passed its zenith. (Za'idah said:) I asked Sulayman (al-A'mash): Zuhr? He said: Yes. Then Sayyiduna Abdullah (may Allah be pleased with him) said: "By the One besides whom there is no god, this is the time of this prayer."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 9245