The Buddha taught that the sage does not engage in quarrels (wordy warfare). In the Samyutta Nikaya, iii.11, he said:
"Home he abandons: homeless wandering
The Sage with folk no longer maketh ties.
Empty of Lusts, showing no preference,
With no man wageth wordy warfare more."
For the Buddha, the sage is one who has overcome all delusions (ignorance, desire, anger). In the S.N, iii, 94, the Buddha talked about the impermanence of the five aggregates:
"I quarrel not with the world, brethren. It is the world that quarrels with me. No preacher of the Norm, brethren, quarrels with anyone in the world.... And what is not upheld in the world of Sages, of which I declare "It is not"? That body is permanent, stable, eternal, not subject to decay. That is not upheld in the world of the Sages, ... Feeling, perception, the activities, consciousness is permanent, stable, eternal, not subject to decay...That is not upheld in the world of the Sages, and of that I declare :It is not so.""
The above clearly explains the Buddha's patience when the man spit on him out of anger which is the result of wrong views formed by the man. There is no such thing as an angry man because all feelings are impermanent. The Buddha is not angry with the man but with his disciples who should have known better than to react with anger. By not showing restraint, they are no better than the man who spit on the Buddha.