Commentaries:
This confirms that pride gives birth to more tangible sins. As plowing prepares the earth to produce crops, so pride prepares the way to produce other sins. Some Bibles translate plowing as "lamp," indicating lighting or guiding the path into other sins. Haughty look shows comparison is taking place and reveals the very essence of pride: perverted comparison, a wrong judgment regarding the value or importance of self, skill, intelligence, etc.
John W. Ritenbaugh
Pride, Contention and Unity
The relationship between pride and sin is easily seen, but none seems to exist between either pride or sin and plowing. However, there is a link. Solomon is saying that just as surely as plowing precedes the produce of the earth, so does pride prepare the way for the produce of sin.
In some Bibles "plowing" may be translated "lamp." In this case, pride is depicted as a lamp that guides or lights the way into sin. In his poem, The Divine Comedy, Dante Alighieri listed pride among the seven great sins. In fact, he lists it first because, he concludes, it is the father of the others. Because of what the Bible reveals of Satan and his rebellion, he is probably correct.
John W. Ritenbaugh
Pride, Humility and the Day of Atonement
Library resources that contain this verse: