Al-A'raf 7:142

WawaAAadna moosa thalatheenalaylatan waatmamnaha biAAashrin fatamma meeqaturabbihi arbaAAeena laylatan waqala moosa li-akheehiharoona okhlufnee fee qawmee waaslih walatattabiAA sabeela almufsideen

And We made an appointment with Moses for thirty nights and perfected them by [the addition of] ten; so the term of his Lord was completed as forty nights. And Moses said to his brother Aaron, "Take my place among my people, do right [by them], and do not follow the way of the corrupters."

And We made an appointment with Mūsā for thirty nights, then We supplemented them with another ten. So, the total period fixed by his Lord was forty nights. Mūsā said to his brother Hārūn, “Take my place among my people and keep things right, and do not follow the way of mischief makers.”