What is the ruling on saying the phrase "Kalimatan haraman wa jamʿan" (a word forbidden and collectively) after prayer?

The habit of saying "Haraman" (meaning "may it be sacred" or "may God accept your prayer") and shaking hands after prayer is widespread in some countries. The origin of making this supplication is not problematic, as long as it is not linked to the completion of the prayer. However, considering it as a prescribed remembrance (dhikr mathur) after prayer, or believing it to be among the sunnahs, makes it an innovation (bid'ah). This is what Ibn Baz, Ibn Uthaymin, and Bakr Abu Zayd have indicated. In summary, adhering to this habit as if it were a prescribed remembrance or believing it to be commendable places it in the category of innovations. As for doing it occasionally or making this supplication in a context other than this, there is no harm in it, and gentleness should be exercised in explaining this to people.