The “liar” is probably the man, who makes false excuses for not giving, and so is inferior to the poor man, whose “desire,” the wish to do good, is taken, in the absence of means to carry it into effect, for the act of kindness itself.
SDA Bible Commentary (limited)
Volume 1-7
22. The desire. The meaning of the first clause is not clear. Some interpret the statement as meaning that the intention is what counts in benevolence. A poor man who does all he can to help, even though that be little, is to be honored above one who promises much, but whose word cannot be trusted (see ch.3:27, 28). The LXX renders this verse, “Mercy is a fruit to a man: and a poor man is better than a rich liar.