From the Council of Laodicea, in Phrygia, 343-381

Canon I. According to the ecclesiastical canon, it is fitting that to those who have been freely and legitimately joined in second nuptials, and have not made the copula of nuptials secretly, when a little time has passed and they have applied themselves to prayers and fasts, communion be given by pardon.

The Fathers signify that secret nuptials are not approved by them. A light penance is prescribed because of second nuptials, even legitimate but manifest; if they had been less legitimate or even secret, a graver penance would have been imposed.

Canon X. Those who are of the Church ought not indiscriminately to join their sons or daughters in marriage with heretics.

Canon XXXI. One ought not to contract marriage with any heretic, or to give sons or daughters, but rather to receive, if they profess that they will be Christians.

There is not invalidation but prohibition in these two canons. Cf. Canons XV and XVI of Elvira.

Canon LII. Nuptials or birthdays ought not be celebrated in Lent.

This canon was received in the second Council of Braga, or in the Collection of Canons of Martin of Braga after the middle of the sixth century.