Musnad Abu Ya'la al-Mawsili 106:26

Uthman ibn Abi Shaybah narrated to us, Abu Mu'awiyah narrated to us, Ibn Abi Layla narrated to us, from Hafsah bint 'Azib, from al-Bara', who said: A man came to the Prophet, may Allah bless him and grant him peace, asking him about the prayer times. He ordered Bilal, so he brought forward and delayed [the prayer], and he said: "The time is what is between these two."