Ibn 'Abbas reported that the Messenger of Allah, may Allah bless him and grant him peace, said, "Do not dispute with your brother. Do not make fun of him. Do not make a promise to him and then break it."  

قَالَ رَسُولُ اللهِ ﷺ لاَ تُمَارِ أَخَاكَ وَلاَ تُمَازِحْهُ وَلاَ تَعِدْهُ مَوْعِدًا فَتُخْلِفَهُ