Surah An-Nisa, ayah 103

4:103

فَإِذَا قَضَيۡتُمُ ٱلصَّلَوٰةَ فَٱذۡكُرُواْ ٱللَّهَ قِيَٰمٗا وَقُعُودٗا وَعَلَىٰ جُنُوبِكُمۡۚ فَإِذَا ٱطۡمَأۡنَنتُمۡ فَأَقِيمُواْ ٱلصَّلَوٰةَۚ إِنَّ ٱلصَّلَوٰةَ كَانَتۡ عَلَى ٱلۡمُؤۡمِنِينَ كِتَٰبٗا مَّوۡقُوتٗا ١٠٣

Fa idhā qadaytumus-salawāta fadhkurullāha qiyāman waqu'ūdan wa'alā junūbikum fa idhatma'nantum fa aqīmus-salawāta innas-salawāta kānat 'alal-mu'minīna kitābam mawqūtā

And when you have completed the prayer, remember Allāh standing, sitting, or [lying] on your sides. But when you become secure, re-establish [regular] prayer. Indeed, prayer has been decreed upon the believers a decree of specified times.