The date for this council is unknown, but it is believed to have been held sometime between A.D. 343 and 381. This was the first time the church legislated Sunday observance. Here is an English translation of that particular enactment:
"Christians shall not Judaize and be idle on Saturday but shall work on that day; but the Lord's day they shall especially honour, and, as being Christians, shall, if possible, do no work on that day. If, however, they are found Judaizing, they shall be shut out from Christ."
Council of Laodicea, can. 29, trans. in Charles Joseph Hefele, A History of the Christian Councils, Vol. 2, trans. and ed. by H. N. Oxenham (Edinburgh: T. and T. Clark, 1896), p. 316.