Logion 27

27. Jesus said, “If ye fast not in the world, ye will not find the kingdom. If ye keep not the sabbath as a sabbath, ye will not see the Father.”
Cf. Mk 2:18-22 with respect to the fast and Mk 2:23-28 with respect to the sabbath.

It appears the parallel structure is telling us that these two activities are very like each other, if not identical. We may find the kingdom through fasting, i.e., putting off the distractions of this world. We may see the Father through observance of the sabbath, i.e., devotion to Him on the days especially designated. Perhaps Jesus would not have restricted such worship to a sabbath, but would have taught that whenever we worship the Father, that day is the sabbath.