ynx1:

Shaikh ’Uthaimeen, may Allaah have mercy on him, said:

“The heaviest thing that can be placed on the scales in terms of dealing with people is good manners. Good manners are something expansive and can be employed in buying and selling, renting and leasing, in everything. So when good manners are a part of [one’s] conduct, then all dealings will be good.”

Fataawaa Nurun ’alad-Darb, vol. 6, p. 107.