Abu Hurairah (May Allah be pleased with him) reported:
The Messenger of Allah (ﷺ) said, "The first of man's deeds for which he will be called to account on the Day of Resurrection will be Salat. If it is found to be perfect, he will be safe and successful; but if it is incomplete, he will be unfortunate and a loser. If any shortcoming is found in the obligatory Salat, the Glorious and Exalted Rubb will command to see whether His slave has offered any voluntary Salat so that the obligatory Salat may be made up by it. Then the rest of his actions will be treated in the same manner."[At- Tirmidhi].
App reference: Book 9, Hadith 91
Arabic/English book reference: Book 9, Hadith 1081