“desire.” The Hebrew text reads nephesh (#05315 נָ֫פֶשׁ), which is the soul, and the products thereof, such as attitude, appetite, etc. This is a case where it is important for the translator to help the English reader, who tends to think “person” when he reads “soul.” Although it is not good for a “soul,” a person, to be without knowledge, that is not the force of the verse, which can be determined by the second half of the proverb. If the verse were to read, for example, “a soul without knowledge is not good; And he who makes haste with his feet misses the way,” what would be the connection between the soul without knowledge and the one who is in a hurry? The proverb, as a whole, would not make sense. The first part of the verse refers to “desire,” a product of the soul, without knowledge, and that desire often is accompanied by haste, but the ignorance causes the person to miss the correct way to accomplish his goal.
“makes haste with his feet sins.” This is not a “general statement of truth,” but one that is specific to the context. Lots of people do things quickly without sinning. However, the person who has a desire and then acts quickly to fulfill it without getting informed about the situation frequently makes a mistake.