as the scripture hath said - These words belong to what follows, “Out of his belly, as the scripture hath said, shall flow,” etc. referring not to any particular passage, but to such as Isa 58:11; Joe 3:18; Zec 14:8; Eze 47:1-12; in most of which the idea is that of waters issuing from beneath the temple, to which our Lord compares Himself and those who believe in Him.
out of his belly - that is, his inner man, his soul, as in Pro 20:27.
rivers of living water - (See on Joh 4:13). It refers primarily to the copiousness, but indirectly also to the diffusiveness, of this living water to the good of others.