Psalms 34:3

“O magnify the Lord with me, etc.] The psalmist invites the humble ones, who he knew would rejoice at the goodness of God to him, to join with him in ascribing greatness to the Lord, which is meant by magnifying him; for he cannot be made great by men, only declared how great he is, and that can only be done in an imperfect manner; and let us exalt his name together: by proclaiming him to be the most High; by making mention of his glorious perfections and works, that he be exalted; and by praising him in the highest strains; or by having the high praises of him in their mouths; and there is more pleasure as well as more glory brought to God by doing this in a social way, or by a number of…”

“magnify the Lord--ascribe greatness to Him, an act of praise. together--"alike" (Psa 33:15), or, equally, without exception.”

“O magnify the Lord with me - This seems to be addressed primarily to the “humble,” those referred to in the previous verse. As they could appreciate what he would say, as they could understand the nature of his feelings in view of his deliverance, he calls upon them especially to exult with him in the goodness of God. As he and they had common calamities and trials, so might they have common joys; as they were united in danger and sorrow, so it was proper that they should be united in joy and in praise. The word “magnify’ means literally “to make great,” and then, to make great in the view of the mind, or to regard and treat as great. The idea is, that he wished all, in circumstances similar…”

“Together - Not in place, for David was now banished from the place of God's publick worship, but in affection: let our souls meet, and let our praises meet in the ears of the all - hearing God. Psalms 34:5”

“magnify: Psa 35:27, Psa 40:16, Psa 69:30; Luk 1:46; Act 19:17; Phi 1:20 let us: Psa 33:1, Psa 33:2, Psa 66:8, Psa 103:20-22, Psa 148:1-14; Ch1 29:20; Ch2 29:30; Rev 14:7; Rev 19:5, Rev 19:6 Psalms 34:4”