Charles H. Spurgeon on Psalms 48:9

We have thought. The Hebrew (Mwd) and (Mmd) and (hmd) belong all to the same signification, of quiet, rest, silence, patient expecting, thinking, considering, and must be determined to any of these senses by the context. And here that of expecting or patient waiting, with affiance in him, and without all distrust or repining at his delays, seems to be most proper for it. For coming to the sanctuary to pray for mercy, it is most agreeable to say we wait for it there, as in the place where he hath promised to afford it, in return to prayers. Henry Hammond.

Verses 12-13. In a spiritual sense the towers and bulwarks of Sion are those doctrines of the true faith, which are the strength and glory of the church, which are to be maintained in their soundness and stability against the assaults of heretical teachers, so that they may be transmitted unimpaired to following generations. Origen and Theodoret, quoted by Wordsworth.