Jamieson, Fausset and Brown on Song of Solomon 4:5

5. breasts--The bust is left open in Eastern dress. The breastplate of the high priest was made of "two" pieces, folded one on the other, in which were the Urim and Thummim (lights and perfection). "Faith and love" are the double breastplate (1Th 5:8), answering to "hearing the word" and "keeping it," in a similar connection with breasts (Lu 12:27, 28).

roes--He reciprocates her praise (So 2:9). Emblem of love and satisfaction (Pr 5:19).

feed--(Psa 23:2).

among the lilies--shrinking from thorns of strife, worldliness, and ungodliness (2Sa 23:6; Mt 13:7). Roes feed among, not on the lilies: where these grow, there is moisture producing green pasturage. The lilies represent her white dress (Psa 45:14; Re 19:8).