Rashi on the Prophets and Writings
Psalms 111
a generation of upright ones which will be blessed, will be his seed.
He shone a light in the darkness Heb. זרח [the “kal” conjugation], like הזריח, [the “hiph’il” or causative conjugation]. Its midrashic interpretation is that He Himself, so to speak, becomes a light for them, as (above 27:1): “The Lord is my light and my salvation.”
Good is the man who is gracious, etc. who is gracious to the poor and lends [to] them, and is not strict, saying, “I cannot afford it,” but [instead] his things, which he needs for himself, in food, drink, and clothing, he conducts with moderation and with a measure, and he spares his property.
his heart is steadfast His heart is faithful to His Maker.
His heart is steadfast He leans on and trusts in the Holy One, blessed be He.
A wicked man will see and become angry Heb. וכעס, an expression of a verb in the past tense, equivalent to ויכעס [i.e., the “vav” converts the past tense to the future]. Therefore, it is vowelized half with a “kamatz” and half with a “pattah,” and the accent is at the end of the word.
You arrive at the cited line; the whole work is yours to read around it. The text is set from the cited public-domain edition.