"Soon they will become regretful," meaning: in a little while; the 'mim' (the letter M) is an auxiliary (silah), according to the tafsir of al-Suddi.
Muhammad said: It is an auxiliary, additive letter, used for the purpose of emphasis.
﴿عَمَّا قَلِيل ليصبحن نادمين﴾ يَعْنِي: عَنْ قَلِيلٍ وَالْمِيمُ صِلَةٌ، فِي تَفْسِيرِ السُّدِّيِّ.
قَالَ مُحَمَّدٌ: هِيَ صِلَةٌ زَائِدَةٌ؛ بِمَعْنَى التَّوْكِيدِ.
