PROPHET MUHAMMAD (ﷺ) said:
Whoever sends Salah (Blessings) upon me once, ALLAH
1) will send Salah (Blessings) upon him tenfold,
2) And will erase ten sins from him,
3) And will raise him ten degrees in status.

Narrated: Umar bin Al-Khattab
Indeed the supplication stops between the heavens and the earth.
Nothing of it is raised up until you send Salat (Read Darood) upon your Prophet (ﷺ).

At-Tufail bin Ubayy bin Ka'b narrated from his father who said:
"When a third of the night had passed, the Messenger of Allah (ﷺ) stood and said:
'O you people! Remember Allah! Remember Allah! The Rajifah is coming, followed by the Radifah, death and what it brings is coming, death and what it brings is coming!'"
Ubayy said: "I said: 'O Messenger of Allah (ﷺ)! Indeed I say very much Salat (Read Darood) for you. How much of my Salat should I make for you (ﷺ)?'
He (ﷺ) said: 'As you wish.'"
[He said:] "I said: 'A fourth?'
He (ﷺ) said: 'As you wish. But if you add more it would be better for you.'
I said: 'Then half?'
He (ﷺ) said: 'As you wish. And if you add more it would be better [for you].'"
[He said:] "I said: 'Then two-thirds?
'He (ﷺ) said: 'As you wish, but if you add more it would be better for you.'
I said: 'Should I make all of my Salat for you?'
He (ﷺ) said: 'Then your problems would be solved and your sins would be forgiven.'"

`Amr bin Malik Al-Janbi narrated that he heard Fadalah bin `Ubaid saying:
“The Prophet (ﷺ) heard a man supplicating in his Salat but he did not send Salat (Read Darood) upon the Prophet (ﷺ), so the Prophet (ﷺ) said: ‘This one has rushed.’ Then he called him and said to him, or to someone other than him: ‘When one of you performs Salat, then let him begin by expressing gratitude to Allah and praising Him. Then, let him send Salat upon the Prophet (ﷺ), then let him supplicate after that, whatever he wishes.’”

Fadalah bin Ubaid narrated:
“While the Messenger of Allah (ﷺ) was seated, a man entered and performed Salat, and he said: ‘O Allah, forgive me, and have mercy upon me.’ The Messenger of Allah (ﷺ) said: ‘You have rushed, O praying person. When you perform Salat, and then sit, then praise Allah with what He is deserving of, and send Salat (Read Darood) upon me, then call upon Him.’” He said: “Then another man performed Salat after that, so he praised Allah and sent Salat upon the Prophet (ﷺ). The Prophet (ﷺ) said to him: ‘O praying person! Supplicate, and you shall be answered.’”