Aside from the celebration of Mass, there are important traditions, seemingly not founded from Christ himself, or from Scripture, which state and reinforce unity, nd which are assumed to be grounded in the apostolic tradition:
26. The church of Christ is made present and signified in a given place and in a given time by the local or particular churches, which through the liturgy reveal the church in its true nature. (Cf. Lumen Gentium 28; also 26.) That is why every particular church must be united with the universal church not only in belief and sacramentals, but also in those practices received through the church as part of the uninterrupted apostolic tradition. (Cf. St. Irenaeus, Against the Heresies, III, 2, 1-3; 3, 1-2: Sources Chretiennes, 211, 24-31; cf. St. Augustine, Letter to Januarius 54, 1: PL 33, 200: “But regarding those other observances which we keep and all the world keeps, and which do not derive from Scripture but from tradition, we are given to understand that they have been ordained or recommended to be kept by the apostles themselves or by the plenary councils, whose authority is well founded in the church”; cf. Redemptoris Missio, 53-4; cf. Congregation for the Doctrine of the Faith, Letter to Bishops of the Catholic Church on Certain Aspects of the Church Understood as Communion, May 28 1992, Nos. 710.) This includes, for example, daily prayer, (Cf. SC 83) sanctification of Sunday and the rhythm of the week, the celebration of Easter and the unfolding of the mystery of Christ throughout the liturgical year, (Cf. SC 102, 106, appendix) the practice of penance and fasting, (Cf. Paul VI, apostolic constitution Paenitemini, Feb. 17, 1966: AAS 58 (1966), 177-198.) the sacraments of Christian initiation, the celebration of the memorial of the Lord and the relationship between the Liturgy of the Word and the eucharistic liturgy, the forgiveness of sins, the ordained ministry, marriage and the anointing of the sick.