Birds are divided in the Mosaic law into two classes, (1) the clean ( Leviticus 1:14-17 ; 5:7-10 ; 14:4-7 ), which were offered in sacrifice; and (2) the unclean ( Leviticus 11:13-20 ). When offered in sacrifice, they were not divided as other victims were ( Genesis 15:10 ). They are mentioned also as an article of food ( Deuteronomy 14:11 ). The art of snaring wild birds is referred to ( Psalms 124:7 ; Proverbs 1:17 ; 7:23 ; Jeremiah 5:27 ). Singing birds are mentioned in Psalms 104:12 ; Eccl 12:4 . Their timidity is alluded to ( Hosea 11:11 ). The reference in Psalms 84:3 to the swallow and the sparrow may be only a comparison equivalent to, "What her house is to the sparrow, and her nest to the swallow, that thine altars are to my soul."