Tahdhīb al-Aḥkām 2, record 74 of the digital edition

Translation

Narrated by Ahmad ibn Muhammad ibn ‘Isa, from al-Hasan ibn Mahbub, from Ibrahim al-Karkhi, who said: I asked Abu al-Hasan Musa (a.s): “When does the time of Dhuhr begin?” Imam (a.s) said: “When the sun passes the meridian.” I asked: “When does its time end?” Imam (a.s) said: “After four forearms (aqdam) have passed from its zenith. Verily, the time of Dhuhr is narrow, not like other times.” I asked: “When does the time of ‘Asr begin?” Imam (a.s) said: “The end of the time of Dhuhr is the beginning of the time of ‘Asr.” I asked: “When does the time of ‘Asr end?” Imam (a.s) said: “The time of ‘Asr is until the sun sets, and that is in case of an excuse, and it is a form of negligence.” I said to him: “If a man were to pray Dhuhr after four forearms had passed from the sun's zenith, would he be considered, in your view, as not having fulfilled it?” Imam (a.s) said: “If he did that deliberately to oppose the Sunnah and the prescribed time, it would not be accepted from him, just as if a man were to delay ‘Asr until it is near sunset, deliberately, without excuse, it would not be accepted from him. Verily, the Messenger of Allah (swt), may Allah (swt) bless him and his family, assigned times for the obligatory prayers and set boundaries for them in his Sunnah for the people. So whoever turns away from one of his obligatory Sunnahs is like one who turns away from the obligations of Allah (swt), the Exalted.”

Translation: Haydar Ali Shaykh ibn Muhammad — published with the edition, reproduced verbatim.