Albert Barnes Commentary Isaiah 58:10

"and if thou draw out thy soul to the hungry, and satisfy the afflicted soul: then shall thy light rise in darkness, and thine obscurity be as the noonday;" — Isaiah 58:10 (ASV)

And if you draw out your soul to the hungry - Lowth, on the authority of eight manuscripts, renders this, ‘If you bring forth your bread to the hungry.’ So the Syriac and Noyes. But the authority is not sufficient to justify the change in the text, nor is it necessary. The word ‘soul’ here is synonymous with heart, or benevolent affection; and the idea is, if they expressed benevolent affection or kindness toward those in want.

Then shall your light rise in obscurity - That is, it will be as if the cheerful light of the sun should rise amidst the shades of midnight. The sense is, that their calamities and trials would be suddenly succeeded by the bright and cheerful light of prosperity.