وَلَا أَجِدُ فِي جِرَابِي مُضْغَةً
Nor could I find even a morsel in my bag.
جِرَاب is a bag or pouch. مُضْغَة literally conveys a small piece that could be chewed, here a tiny morsel of food.
The preceding line described need in general terms. This one makes it concrete through a single morsel. Lacking even so little reveals the depth of his poverty.