Job 32:18

For I am full of matter
Or "full [of] words" ^F25; not of mere words, such that have nothing solid and substantial in them; this is the character of a fool, ( Ecclesiastes 10:14 ) ; nor was Elihu a loquacious talkative man, as Job is charged to be, a man full of talk, ( Job 11:2 ) ; but he was full of words, which had fulness of matter in them, which were to the purpose, and contained strong reasonings and solid arguments; his mind was full of them, and he could easily fill his mouth with them, and was not easy until he had uttered them: so an able minister of the word may be said to be full of words, of the wholesome words of our Lord Jesus, of useful doctrines, when the word of Christ dwells richly in him, and he has a rich treasure in an earthen vessel, is full of the blessing of the Gospel of Christ; has a large knowledge of Gospel truths, a real experience of them in the heart, great gifts to express them to others, and is full of power and of the Spirit of God to declare them, as this good man was:

the spirit within me constraineth me,
or "the spirit of my belly" ^F26; alluding to wind pent up therein, which, unless expelled, gives great uneasiness and pain: he either means the Spirit of God within him, as in ( Job 32:8 ) , by whom the prophets were inspired and spoke, by whom ordinary ministers of the word are qualified for their work, and by whom they are led into all truth, and who presses and obliges them to speak what they know; there is a necessity upon them to preach the Gospel wholly and faithfully, and a woe unto them if they do not: or else his own spirit, influenced and actuated by the Spirit of God; as the spirit of the Apostle Paul was stirred up in him to speak, when he saw the idolatry and superstition of the people of Athens, ( Acts 17:16 ) ; so love to God and Christ, and the souls of men, the honour of God, and interest of religion, constrain the ministers of Christ to speak in his name, notwithstanding all the opposition made unto them, and reproach cast upon them.