Psalms 66:15
I will offer unto thee burnt sacrifices of fatlings, with the incense of rams; I will offer bullocks with goats. Selah. I will offer unto thee burnt sacrifices of fatlings, with the incense of rams; I will offer bullocks with goats. Selah.
The vow is to bring costly animal offerings of fatlings, rams, bullocks, and goats to God as an act of worship. That vow stands within a setting that joins the promised offerings with open testimony to God's goodness and with praise for answered prayer. The offerings God values in that worship are joined to a broken and contrite heart. The praise that accompanies the offerings must itself come from the heart.