《旧唐书·列传·卷三十九》
兵，金性，金克木，春盛德在木上，而去举金害盛德，违逆生气，如果 孟春行冬令，那么水涝而败坏庄稼，霜雪大至，首种不入。 
兵金性，克木，春盛德在木，而举金以害盛德，逆生气。 孟春行冬令，则水潦为败，雪霜大挚，首种不入。 
Weapons are made of metal and metal restrains wood, but the royal aura in spring is on wood. So to use metal to harm the royal aura is against the growth of all living things. If we practice the winter regulations in the first Moon of spring, it would lead to floods and destroy crops; frost and snow would come early and the first seeds would not grow. 