This is a metaphor for a person who becomes more wealthy by being generous. AT: "Some people give freely to others and yet become more wealthy" (See: [[rc://en/ta/man/translate/figs-metaphor]])
You may need to make explicit that the person scatters seeds for crops to grow. AT: "one who scatters much seed" (See: [[rc://en/ta/man/translate/figs-explicit]] and [[rc://en/ta/man/translate/figs-metaphor]])
# will accumulate even more
"will gain even more"
# withholds what he should give
This refers to a person who thinks that he can become rich by refusing to be generous.