Colossians 1:9

For this cause we also
Not merely for their love to the apostle, and the rest that were with him; which sense is too much contracted, and carries some appearance of meanness and selfishness; but because of their faith in Christ, their love to all the saints, and the good hope they had of eternal happiness; and because they had heard the Gospel, and truly knew it, and sincerely professed it: therefore,

since the day we heard [it], do not cease to pray for you, and to
desire;
which shows that the apostles prayed without ceasing; not that they were every moment praying, without intermission, but that they were frequent and constant every day at the throne of grace; and as often as they were there, they were mindful of these Colossians, even ever since they heard of their reception of the Gospel, of their profession of it, and of the fruit it brought forth in them; and in their petitions "prayed" and "desired", earnestly and importunately entreated God on their behalf:

that ye might he filled with the knowledge of his will;
the will "of God", as the Syriac version reads it, by which is meant, not the secret will of God, according to the counsel of which he does all things in nature, providence, and grace, but his revealed will; and that either as it is signified in the law, which declares the good, and perfect, and acceptable will of God, relating to what he would have done, or avoided by his creatures; or rather, as it is exhibited in the Gospel, which contains the will of God respecting the salvation of his chosen ones; as that it is his will that Christ should obtain eternal redemption for them, to do which he voluntarily substituted himself in their room, came into this world, and has accomplished it; and that all those that are redeemed by Christ should be regenerated by the Spirit; and that whoever sees the Son, and believes in him, should not perish, but have everlasting life; as also, that all those whom he has chosen in Christ, and given to him, and he has redeemed by his blood, and who are sanctified by his Spirit, none of them should be lost, but that they should be all saved with an everlasting salvation. Now the apostle does, not pray that they might have a "knowledge" of this will of God, for some knowledge of it they had already; they had heard of the hope laid up in heaven, in the truth of the word of the Gospel; they had not only had the external, revelation, and had heard the Gospel outwardly preached, but they had known truly the grace of God; and therefore what he asks for is, that they might be "filled" with the knowledge of it; which supposes that they had knowledge, but it was not full and complete; it was imperfect, as is the knowledge of the best of saints in this life; and that they might have a larger measure of it, and such a fulness of it as they were capable of in the present state, and not such an one as the saints will have in heaven, when they shall know even as they are known. He adds,

in all wisdom and spiritual understanding;
his meaning is, that they might be led into all the wisdom of God, which is so largely displayed in the revelation of his will concerning the salvation of his people, which is made in the Gospel; which is the manifold wisdom of God, wherein he has abounded in all wisdom and prudence; and contains such a scheme of things, so wisely contrived and formed, that angels desire to look into it; and that they might have a "spiritual understanding" of the mysteries of grace, without which they cannot be discerned to spiritual advantage, nor indeed without the spirit of wisdom and revelation in the knowledge of them: and the Ethiopic version renders it, by "the prudence of the Holy Ghost": who searches the deep things of God, and reveals them to the saints, and improves and increases their spiritual and experimental knowledge of them, which is what is here intended.