Gregorius Magnus, Moralia in Iob 18:26 (CCSL 143A:911)
And I found him commenting on this place in Job: Gold has a place in which it is melted,Job 28:1 (V)
and the rest. Gold is the mass of saints; the smelter is the unity of the Church; the fire is the suffering of martyrdom. He, therefore, who is burned outside of the unity of the Church can be melted down, but cannot be purified.Gregorius Magnus, Moralia 18:26 (CCSL 143A:911)
Whence Paul also says: If I deliver my body to be burned, but have not love, I gain nothing1 Cor. 13:3
[...] I also found him interpreting the following verse in the same sense in another place: Be thou to me God a protector, and a strong fortress that you might save me.Ps. 70:3 (V)
And he does not find a fortified place (that is, safe) either in heaven for the angels, or on earth for men, except the humble unity which the archangel cast away and now is the devil, and which man, imitating him, cast aside and now is mortal.Gregorius Magnus, Homilia in Hiezechiel 1:9.22 (CCSL 142:136)
And I fear this. You consider carefully, brothers, whether it is with good reason or through cowardice.