"And tell My servants to say that which is best." This means that they should command them with what Allah has commanded them, and forbid them from what Allah has forbidden them. "Indeed, Satan induces [dissension] among them," meaning: he corrupts. "Indeed, Satan has ever been to mankind a clear enemy," manifest in his enmity.
﴿وَقُلْ لِعِبَادِي يَقُولُوا الَّتِي هِيَ أحسن﴾ هُوَ أَنْ يَأْمُرُوهُمْ بِمَا أَمَرَهُمُ اللَّهُ بِهِ، وَيَنْهَوْهُمْ عَمَّا نَهَاهُمُ اللَّهُ عَنْهُ ﴿إِنَّ الشَّيْطَانَ يَنْزَغُ بَينهم﴾ أَيْ: يُفْسِدُ ﴿إِنَّ الشَّيْطَانَ كَانَ للْإنْسَان عدوا مُبينًا﴾ بَين الْعَدَاوَة.