It was narrated that Ibn Abbas said, “When the Prophet came to Al-Madinah, they were the worst people in weights and measures. Then Allah, Glorious is He, revealed: “Woe to the mutaffifeen (those who shortchange others),” and they became the best of people in how they dealt with weights and measures after that.” [Ibn Majah]
Shortchanging, or tatfeef, is to cheat or be stingy in the way you give back. Sh. Omar Suleiman describes the different concepts of tatfeef and how we can avoid shortchanging others.