زَيْدٌ إِنْ جَاءَنِي فَأَكْرَمْتُهُ
Translation: As for Zayd, if he came to me, I honoured him.
«إِنْ» introduces a condition. The hidden subject of «جَاءَنِي» is Zayd; the object pronoun «ـهُ» in «أَكْرَمْتُهُ» also refers to him. Together they link the conditional statement to the mubtadaʾ.