Mediator Dei §123

¹²³ When the Mass, which is subject to special rules of the liturgy, is over, the person who has received holy communion is not thereby freed from his duty of thanksgiving; rather, it is most becoming that, when the Mass is finished, the person who has received the Eucharist should recollect himself, and in intimate union with the divine Master hold loving and fruitful converse with Him. Hence they have departed from the straight way of truth, who, adhering to the letter rather than the sense, assert and teach that, when Mass has ended, no such thanksgiving should be added, not only because the Mass is itself a thanksgiving, but also because this pertains to a private and personal act of piety and not to the good of the community.