Who are "the saints" in Psalm 149?

The psalm's word is chasid, which Brown-Driver-Briggs gives as "kind, pious" (tap saints). It has the word three times: "the assembly of the saints" (149:1), "Let the saints rejoice in honor" (149:5), and "All his saints have this honor" (149:9). Between those lines it calls on "Israel" and "the children of Zion" (149:2), and speaks of "his people" and "the humble" (149:4). The psalm doesn't say whether these are all one group. The verse just before it, the last of Psalm 148, puts two of them together: "the praise of all his saints, even of the children of Israel, a people near to him" (Psalm 148:14). In another psalm God says who his saints are: "Gather my saints together to me, those who have made a covenant with me by sacrifice" (Psalm 50:5). These notes don't say more than those verses do.