This is the form III verb (active voice). There are two syntactical possibilities that amount to the same meaning, i.e. the Prophet and the men fought together and did not weaken from the hardships they faced.

This is the form I verb (passive voice). Here the syntax gives rise to distinct meanings. The first meaning is that earlier believers did not cease defending the cause when their Prophet was killed. The second meaning is that when many believers were killed, those who remained alive continued to fight and did not weaken.

Abū Jaʿfar al-Madanī

Ibn ʿĀmir al-Shāmī

Nāfiʿ al-Madanī

Ḥamzah al-Zayyāt

Ibn Kathīr al-Makkī

Khalaf al-Bazzār

Abū ʿAmr al-Baṣrī

al-Kisāʾī

Yaʿqūb al-Ḥaḍramī

ʿĀṣim al-Kūfī

Ibn Wardan

Ibn Jammaz

Hishām

Ibn Dhakwān

Warsh

Qalun

Khalaf

Khallad

Al-Bazzi

Qunbul

Isḥaq

Idrīs

Ad-Duri

As-Susi

Abu al-Harith

Ruwais

Rawḥ

Shuʿbah

Ḥafṣ

وَكَأَيِّن مِّن نَّبِىٍّ قَـٰتَلَ مَعَهُۥ رِبِّيُّونَ كَثِيرٌ فَمَا وَهَنُوا۟ لِمَآ أَصَابَهُمْ فِى سَبِيلِ ٱللَّهِ وَمَا ضَعُفُوا۟ وَمَا ٱسْتَكَانُوا۟ ۗ وَٱللَّهُ يُحِبُّ ٱلصَّـٰبِرِينَ