Charles H. Spurgeon on Psalms 32:9

Be ye not as the horse, or as the mule, etc. According to the several natures of these two beasts, the fathers and other expositors have made several interpretations; at least, several allusions. They consider the horse and the mule to admit any rider, any burden, without discretion or difference, without debate or consideration; they never ask whether their rider be noble or base, nor whether their load be gold for the treasure, or roots for the market. And those expositors find the same indifference in an habitual sinner to any kind of sin; whether he sin for pleasure, or sin for profit, or sin but for company, still he sins. They consider in the mule, that one of his parents being more ignoble than the other, he is like the worst, he hath more of the ass than of the horse in him; and they find in us, that all our actions and thoughts taste more of the more ignoble part of the earth than of heaven. St. Hierome thinks fierceness and rashness to be presented in the horse, and sloth in the mule. And St. Augustine carries these two qualities far; he thinks that in this fierceness of the horse the Gentiles are represented, which ran far from the knowledge of Christianity; and by the laziness of the mule the Jews, who came nothing so fast, as they were invited by their former helps to the embracing thereof. They have gone far in these allusions and applications; and they might have gone as far further as it had pleased them; they have sea room enough, that will compare a beast and a sinner together; and they shall find many times, in the way, the beast the better man. John Donne.