70 Many of the peoples entrusted to the ministry of the missionaries take great delight in music and beautify the ceremonies dedicated to the worship of idols with religious singing. It is not prudent, then, for the heralds of Christ, the true God, to minimize or neglect entirely this effective help in their apostolate. Hence the preachers of the Gospel in pagan lands should sedulously and willingly promote in the course of their apostolic ministry the love for religious song which is cherished by the men entrusted to their care. In this way these people can have, in contrast to their own religious music which is frequently admired even in cultivated countries, sacred Christian hymns in which the truths of the faith, the life of Christ the Lord and the praises of the Blessed Virgin Mary and the Saints can be sung in a language and in melodies familiar to them.
Source: Musicae Sacrae (Vatican.va)