Does the noble verse, "And [by] the soul and He who proportioned it and inspired it [with discernment of] its wickedness and its righteousness – He has succeeded who purifies it, and he has failed who corrupts it," indicate that any human disposition is subject to change, and can a stingy person become generous or normal, and are there historical Islamic examples of this?

Good manners include both innate qualities and those acquired through learning and self-restraint. Stinginess, however, is a vile disease that requires great struggle against the self to overcome. The heart is ever-changing, in the hand of Allah, who turns it as He wills. To be rid of stinginess, the miser should familiarize himself with the verses of the Qur’an, the Prophetic traditions, the sayings of the righteous predecessors, and the stances of generous people. He should also accustom himself to spending and giving, little by little, for whoever strives in the way of Allah, Allah will surely guide him.