The Significance of Prayer in Islam: A Key to Success and Salvation
The Prophet ﷺ said:
“Indeed the first deed by which a servant will be called to account on the Day of Resurrection is his Salat (prayers).
If it is complete, he is successful and saved, but if it is defective, he has failed and lost.
So if something is deficient in his obligatory (prayers) then the Lord, Mighty and Sublime says:
‘Look! Are there any voluntary (prayers) for my worshipper?’
So with them, what was deficient in his obligatory (prayers) will be completed. Then the rest of his deeds will be treated like that.”
Tirmidhi 413 (Sahih)