Surah As-Saf 61:4

إِنَّ ٱللَّهَ يُحِبُّ ٱلَّذِينَ يُقَـٰتِلُونَ فِى سَبِيلِهِۦ صَفًّا كَأَنَّهُم بُنْيَـٰنٌ مَّرْصُوصٌ

Indeed, Allāh loves those who fight in His cause in a row as though they are a [single] structure joined firmly.

Translation: Saheeh International

Tafsir

Indeed God loves He assists and honours those who fight for His cause in ranks saffan is a circumstantial qualifier in other words understand it as sāffīna as if they were a solid structure with all of its parts compacted together firm.

Excerpt from Tafsir al-Jalalayn, commentary on 61:4, via Quran.com. The reader has the full commentary and 9 more tafsirs.