In ancient Israel, making a vow or offering to God was a serious commitment, often involving the dedication of an animal. This verse underscores the principle that once something is dedicated to God, it is set apart as holy and should not be exchanged or substituted. The rule applies regardless of whether the substitute is perceived as better or worse. This reflects a broader biblical theme of integrity and faithfulness in one's commitments.
The act of substitution could imply a lack of sincerity or a change of heart, which is discouraged. By stating that both the original and the substitute become holy, the scripture teaches that once something is offered to God, it transcends ordinary value and becomes sacred. This principle encourages believers to approach their commitments to God with sincerity and respect, recognizing the holiness of what is dedicated to Him. It serves as a reminder of the importance of keeping promises and the spiritual significance of offerings.