What is the interpretation of the Hadith regarding cracking knuckles (joints), and is it always forbidden or only during prayer?

Cracking one's knuckles is makruh (disliked) during prayer because it distracts the worshipper or disturbs others. Abdullah ibn Abbas, may Allah be pleased with both of them, is reported to have said regarding it: "May you lose your mother! You crack your knuckles while you are in prayer!" It does not invalidate the prayer, but it is a form of idleness (عبث). If it occurs in congregational prayer, it disturbs others. A group of scholars have explicitly stated its dislike in the mosque, likening it to interlocking fingers, as both are considered idle acts.