The mystery which hath been hid - The mystery is this: that God had designed to grant the Gentiles the same privileges with the Jews, and make them his people who were not his people. That this is what St. Paul means by the mystery, see Ephesians 3:3, etc.

Made manifest to his saints - It is fully known to all who have embraced the doctrine of Christ crucified; to all Christians.

the mystery.

Romans 16:25,26 Now to him that is of power to establish you according to my gospel, and the preaching of Jesus Christ...

1 Corinthians 2:7 But we speak the wisdom of God in a mystery, even the hidden wisdom, which God ordained before the world to our glory:

Ephesians 3:3-10 How that by revelation he made known to me the mystery; (as I wrote before in few words...

now.

Psalm 25:14 The secret of the LORD is with them that fear him; and he will show them his covenant.

Matthew 13:11 He answered and said to them, Because it is given to you to know the mysteries of the kingdom of heaven, but to them it is not given.

Mark 4:11 And he said to them, To you it is given to know the mystery of the kingdom of God: but to them that are without...

Luke 8:10 And he said, To you it is given to know the mysteries of the kingdom of God: but to others in parables; that seeing they might not see...

2 Timothy 1:10 But is now made manifest by the appearing of our Savior Jesus Christ, who has abolished death...

'All Power'
'Strengthened with all power, according to the might of His glory, unto all patience and longsuffering with joy.'--COL. i. 11 (R.V.). There is a wonderful rush and fervour in the prayers of Paul. No parts of his letters are so lofty, so impassioned, so full of his soul, as when he rises from speaking of God to men to speaking to God for men. We have him here setting forth his loving desires for the Colossian Christians in a prayer of remarkable fulness and sweep. Broadly taken, it is for their perfecting …
Alexander Maclaren—Expositions of Holy Scripture

Twenty-Third Day for the Holy Spirit in Your Own Work
WHAT TO PRAY.--For the Holy Spirit in your own Work "I labour, striving according to His working, which worketh in me mightily."--COL. i. 29. You have your own special work; make it a work of intercession. Paul laboured, striving according to the working of God in him. Remember, God is not only the Creator, but the Great Workman, who worketh all in all. You can only do your work in His strength, by Him working in you through the Spirit. Intercede much for those among whom you work, till God gives …
Andrew Murray—The Ministry of Intercession

Knowledge and Obedience.
"For this cause we also, since the day we heard it, do not cease to pray for you, and to desire that ye might be filled with the knowledge of His will in all wisdom and spiritual understanding; that ye might walk worthy of the Lord unto all pleasing, being fruitful in every good work, and increasing in the knowledge of God; strengthened with all might, according to His glorious power, unto all patience and long-suffering with joyfulness; giving thanks unto the Father."--COL. i. 9-12. The Epistles …
W. H. Griffith Thomas—The Prayers of St. Paul