John Gill Commentary Psalms 119:71

"It is good for me that I have been afflicted; That I may learn thy statutes." — Psalms 119:71 (ASV)

[It is] good for me that I have been afflicted
The good and profit of which he had observed before; (See Gill on Psalms 119:67). The following end being also answered thereby,

that I might learn your statutes ;
to understand them, and to keep them. Afflictions are sometimes as a school to the people of God, in which they learn much both of their duty and of their privileges; and when they are teaching and instructive, they are for good; see (Psalms 94:12) .