Nicene and Post-Nicene Fathers, Ser. II, Vol. XIV:
The Canons of the Councils of Ancyra, Gangra, Neocæsarea, Antioch and Laodicea, which Canons were Accepted and Received by the Ecumenical Synods.: Canon LII

Canon LII.

Marriages and birthday feasts are not to be celebrated in Lent.

Notes.

Ancient Epitome of Canon LII.

Marriage shall not be celebrated in Lent, nor birthdays.

Hefele.

By “birthday feasts” in this canon the natalitia martyrum is not to be understood as in the preceding canon, but the birthday feasts of princes.  This, as well as the preceding rule, was renewed in the sixth century by Bishop Martin of Bracara, now Braga, in Portugal.