يَدْخُلُونَ فِي دِينِ اللَّهِ أَفْوَاجًا
They enter Allah's religion in groups. (110:2)
Afwājan, the plural of fawj, is commonly analyzed as an accusative circumstantial expression describing the people entering. Its indefinite form does not name a particular fixed group; it portrays arrival in successive groups.
After the general expression al-nās, afwājan specifies the manner of entry. It conveys a vivid sense of collective movement and multiplicity without yielding an exact numerical count from indefiniteness alone.