That the yoke of the law was heavy, which is cast off by us, and that the Lord's yoke is easy, which is taken up by us
In the second Psalm: “Wherefore have the heathen been in tumult, and the peoples meditated vain things? The kings of the earth have stood up, and their princes have been gathered together against the Lord, and against His Christ. Let us break their bonds asunder, and cast away from us their yoke.” Also in the Gospel according to Matthew: “Come unto me, you who labour and are burdened, and I will make you to rest. Take my yoke upon you, and learn of me: for I am meek and lowly of heart, and you shall find rest for your souls. For my yoke is good, and my burden is light.” Also in the Acts of the Apostles: “It seemed good to the Holy Ghost, and to us, to impose upon you no other burden than those things which are of necessity, that you should abstain from idolatries, from shedding of blood, and from fornication. And whatsoever you would not to be done unto you, do not to others.”
Source: The Treatises of Cyprian (New Advent)