[Indeed, the righteous are in a place of security] - meaning: a station [secure] - that is: they are safe therein from changes.
Muhammad said: Whoever reads "muqamin" with a damma on the mim, it is derived from the saying: "aqama maqaman" (he established a station). And whoever reads it with a fatha on the mim, it is derived from the saying: "qama yaqumu" (he stood, he stands).
﴿إِن الْمُتَّقِينَ فِي مقَام﴾ فِي منزل ﴿امين﴾ أَي: هم آمنون فِيهِ من الغِيَرِ.
قَالَ محمدٌ: من قَرَأَ ﴿مُقامٍ﴾ بِرَفْع الْمِيم فَهُوَ من قَوْلهم: أَقَام مُقَامًا، وَمن قَرَأَ بِفَتْح الْمِيم فَهُوَ من قَوْلهم: قَامَ يقوم.