According to the Mosaic Law, the Israelites were to offer specific sacrifices. The sacrifices were to be unblemished because they pointed to Jesus ’ perfect sacrifice.
فَإِنْ لَمْ يَكُنْ فِي وُسْعِ ٱلْأُمِّ أَنْ تُقَدِّمَ شَاةً ،‏ سُمِحَ لَهَا أَنْ تُقَدِّمَ زَوْجَ تِرْغَلٍّ أَوْ فَرْخَيْ يَمَامٍ .‏