كَيْدَهُم

كَيْدَهُم is a phrase (شِبْهُ الجُمْلَةِ) consisting of a possessed noun and an attached, third-person, plural, possessive pronoun

PhraseNoun / NounNoun Noun
شِبْهُ الجُمْلَةِمُضَافٌ وَ مُضَافٌ إِلَيْهِمُضَافٌ إِلَيْهِمُضَافٌ
PhrasePossessive compoundPossessive noun/ownerNoun possessed/owned
their planكَيْدَهُم=هُم+كَيْدَ
their plantheirsplan of
Surah/Below is the only verse in the holy Quran containing the possessive nominal compoundكَيْدَهُم
Verse
105-2Did He not make their plan go astray?أَلَم يَجْعَلْ كَيْدَهُم فِي تَضْلِيْلٍ