About this passageThe chapter opens with the book's central paradox — acting without acting — and then gives it a practical form: everything difficult was once easy and everything large was once small, so the work is done early, at a size where it does not look like work. The line about repaying injury with kindness sits inside that list rather than being singled out, one item among several ways of not letting a thing grow.
(It is the way of the Tao) to act without (thinking of) acting; to conduct affairs without (feeling the) trouble of them; to taste without discerning any flavour; to consider what is small as great, and a few as many; and to recompense injury with kindness.
(The master of it) anticipates things that are difficult while they are easy, and does things that would become great while they are small. All difficult things in the world are sure to arise from a previous state in which they were easy, and all great things from one in which they were small. Therefore the sage, while he never does what is great, is able on that account to accomplish the greatest things.
He who lightly promises is sure to keep but little faith; he who is continually thinking things easy is sure to find them difficult.
In plainer words
Act without making a production of acting. Handle things without being troubled by them. Taste without fussing over the flavour. Treat the small as large and the few as many. Pay back an injury with kindness. Deal with the hard thing while it is still easy and the big thing while it is still small — every hard thing was easy once, and every big thing was small. So the wise person never tackles anything great, and that is exactly how the great things get done. Someone who promises lightly will not keep much faith, and someone who keeps deciding things are easy will find them hard.
A restatement in modern English, written for this collection. The passage above is the text; this is one way of putting it.