On the Cavalry Commander (6.10-6.11)

The groom must also pay some attention to such points as the following: whether the horse will not easily take the bit when he knows that he has work to do. Willingness to receive the bit is, in fact, so important that a horse that refuses it is quite useless.

But if he is bridled not only when he is going to be ridden, but also when he is taken to his food and when he is led home from exercise, it would not be at all surprising if he seized the bit of his own accord when offered to him.