"But if you do not, then be informed of a war [against you] from Allah and His Messenger," meaning: know that you are at war with Allah and His Messenger, and that you are polytheists (mushrikun).
Muhammad said: Whoever recites it as "fa-adhinu" (without a connected alif) means it is from "adhana, yu'dhinu," meaning: to inform. Whoever recites it as connected ("fa'dhanu") means it is from "adhina, ya'dhanu"; if one listens to something and hears it. "But if you repent," meaning: if you embrace Islam, "you shall have your principal sums," meaning: the excess is nullified if it remained as a debt owed by the sought party. "You shall not wrong," by taking the excess, "nor be wronged," by having anything taken from your principal sums.
﴿فَإِنْ لَمْ تَفْعَلُوا فَأْذَنُوا بِحَرْبٍ من الله وَرَسُوله﴾ أَي: فاعلموا أَنكُمْ بِحَرب من اللَّه وَرَسُوله، وأنكم مشركون.
قَالَ مُحَمَّد: من قَرَأَ ﴿فَآذِنُوا﴾ غير مَوْصُولَة فَهُوَ من: آذن يُؤذن؛ أَي: أعلم، وَمن قَرَأَهَا مَوْصُولَة فَهِيَ من: أذن يَأْذَن؛ إِذا أصغى للشَّيْء وسَمعه. ﴿وَإِنْ تُبْتُمْ﴾ أَي: أسلمتم ﴿فَلَكُمْ رُءُوسُ أَمْوَالِكُمْ﴾ يَقُولُ: يبطل الفَضْل إِذا كَانَ بَقِي دينا عَلَى الْمَطْلُوب ﴿لَا تظْلمُونَ﴾ فتأخذون الْفضل ﴿وَلَا تظْلمُونَ﴾ من رُءُوس أَمْوَالكُم شَيْئا.
