With the conversion of the people of Taif to Islam, the mission of Makkah was completed. The Holy Prophet and his companions performed the "Umrah", and thereafter returned to Madina. Eight years earlier the Muslims had escaped from Makkah and oppressed people, now they were the masters of Makkah, Madina, and a greater part of Arabia. That was verily a positive proof of the truth of Islam. Thus God fulfilled all the promises that He had made with His prophet.
"When a person dies, his works end, except for three: ongoing charity, knowledge that is benefited from, and a righteous child who prays for him."
Prophet Mohammed (PBUH)
"The best of what a man leaves behind are three: a righteous child who supplicates for him, ongoing charity the reward of which reaches him, and knowledge that is acted upon after him."
Sunan Ibn Mājah
"Every day two angels come down from Heaven and one of them says, 'O Allah! Compensate every person who spends in Your Cause,' and the other (angel) says, 'O Allah! Destroy every miser.'"
Sahih Bukhari