إِيْلَافِ

A word in the Arabic language will either be 1) a verb or 2) a noun or 3) a particle – إِيْلَافِ is a noun

A noun may either be 1) Definite or indefinite 2) Masculine or feminine 3) Singular, dual or plural 4) Nominative, accusative or genitive

إِيْلَافٌ is the natural state of the definite noun and it changes to إِيْلَغفٍ due to: 1) a preposition that precedes it or 2) a possessed noun that precedes it or 3) it’s a noun of dependent declension a) نَعْتٌ / صِفَطٌ adjectives b) التَّوْكِيْدُ emphatic c) المَعْطُوْفٌ conjunction d) البَدَلُ synonym

إِيْلَافٍ loses it’s indefinite sign, becoming إِيْلَافِ due to it being a possessed noun

Unity, compact, alliance, covenant for the purpose of trade, obligation involving responsibility for safety and protection, attachment

To be accustomed, join together, unite, reconcile, become tame, bring together

Grammatical analysis of إِيْلَافِ
اسْمٌ مَجْرُوْرٌ بِالكَسْرَةِ الزَّاهِرَةِ وَهُوَ مُضَافٌ
Surah/Below are the only 2 verses in the holy Quran containing the possessed nounإِيْلَافِ
Verse
106-1For the familiarity of the Quraishلِإِيْلَافِ قُرَيْشٍ
106-2Their familiarity with the journey of winter and summerإِيْلَافِهِمْ رِحْلَةَ الشِّتَآءِ وَالْصَّيْفِ