Tafsir of Al-Fajr 89:18

(And you do not encourage [one another] (wa lā taḥāḍḍūn)) – with the omission of one of the two tā’s from (tataḥāḍḍūn). That is: none of you encourages and urges another to feed the needy. Thus, "food" (ṭa‘ām) is an infinitive meaning "to feed," similar to "gift" (‘aṭā’) meaning "to give."

Abu Hayyan claimed that it is preferable for it to mean the edible thing itself, in which case the expression implies an omitted genitive, meaning: "to bestow the food of the needy." "The needy" (al-miskīn) is intended here in a sense that encompasses the poor (al-faqīr).

‘Abdullah [ibn Mas‘ud], ‘Alqama, Zayd ibn ‘Ali, ‘Abdullah ibn al-Mubarak, and al-Shirazi, narrating from al-Kisa’i, recited it in the same manner as the majority, except that they gave the tā’ in taḥāḍḍūn a ḍamma (u-vowel), deriving it from muḥāḍḍa (mutual provocation).

Abu ‘Amr, as well as al-Hasan and those with him who were heard, recited it as wa lā yaḥuḍḍūn (they do not encourage) with a yā’ indicating the third person, and no alif after the ḥā’. The rest of the seven [canonical reciters] recited it with a tā’ indicating the second person, and likewise [without an alif] for both verbs that follow [in the subsequent verse].

As for the verb in both readings, it is permitted that it be transitive with an omitted object. It has been said the object is "themselves," or "your souls," or "their families," or "your families," or "anyone." It is also permitted—and this is the most preferable view—that it be treated as having the status of an intransitive verb for the sake of generalization.