Charles H. Spurgeon on Psalms 66:15

I will offer unto thee burnt sacrifices of fatlings. The good man will give his best things to God. No starveling goat upon the hills will he present at the altar, but the well fed bullocks of the luxuriant pastures shall ascend in smoke from the sacred fire. He who is miserly with God is a wretch indeed. Few devise liberal things, but those few find a rich reward in so doing. With the incense of rams. The smoke of burning rams should also rise from the altar; he would offer the strength and prime of his flocks as well as his herds. Of all we have we should give the Lord his portion, and that should be the choicest we can select. It was no waste to burn the fat upon Jehovah's altar, nor to pour the precious ointment upon Jesus' head; neither are large gifts and bountiful offerings to the church of God any diminution to a man's estate: such money is put to good interest and placed where it cannot be stolen by thieves nor corroded by rust. I will offer bullocks with goats. A perfect sacrifice, completing the circle of offerings, should show forth the intense love of his heart. We should magnify the Lord with the great and the little. None of his ordinances should be disregarded; we must not omit either the bullocks or the goats. In these three verses we have gratitude in action, not content with words, but proving its own sincerity by deeds of obedient sacrifice. Selah. It is most fit that we should suspend the song while the smoke of the victims ascends the heavens; let the burnt offerings stand for praises while we meditate upon the infinitely greater sacrifice of Calvary.