What is the ruling on mentioning people behind their backs merely for jesting, and what is the way to get rid of this habit?

Neglecting prayer is a grave sin, which many scholars consider an act of disbelief that expels one from the fold of Islam. Therefore, a Muslim should appreciate the blessing of guidance and show gratitude for it in word and deed, and choose righteous companions who assist in obeying Allah. As for mentioning people with what they dislike in their absence, this is backbiting (gheebah), which is forbidden by the Qur'an, Sunnah (definition), and the consensus of the Ummah. Many scholars consider it one of the major sins. One must seek forgiveness from those who have been backbited, unless informing them would spoil affection or cause problems, in which case one should seek forgiveness for them.