ٱنفِرُوا۟ خِفَافًا وَثِقَالًا وَجَـٰهِدُوا۟ بِأَمْوَٰلِكُمْ وَأَنفُسِكُمْ فِى سَبِيلِ ٱللَّهِ ۚ ذَٰلِكُمْ خَيْرٌ لَّكُمْ إِن كُنتُمْ تَعْلَمُونَ
Infiroo khifaafanw wa siqaalanw wa jaahidoo bi amwaalikum wa anfusikum fee sabeelil laah; zaalikum khairul lakum in kuntum ta'lamoon
Go forth, light or heavy, and strive with your wealth and your lives in the path of God. That is better for you, if you only knew.
Khifāfan wa thiqālan, light and heavy, has been read many ways: lightly or heavily armed, mounted or on foot, young or old, free of dependants or burdened with them. The plurality carries the force — whichever end of a pair a person occupies, the call has already reached them. This was the march to Tabuk in high summer, and the verse just after describes those who would have come had the road been short and the gain quick.