زَيْدٌ: nominative mubtadaʾ.
إِنْ: jussive conditional particle.
جَاءَنِي: past verb in the syntactic position of the jussive conditional verb; implicit subject “he” refers to Zayd, and «نِي» is its object.
فَأَكْرَمْتُهُ: «فَ» connects the response; «تُ» is the doer of “I honoured,” and «هُ» the object, Zayd.
The author gives the conditional construction as a whole as khabar. At this stage, recognise the condition, response and referential link.