There are several contrasts in this verse between earthly fathers and the Father of spirits. They disciplined us for a few days or maybe we could say a few days at a time, or a few minutes at a time, every now and then.
What a glorious thing it is, my tutor is the Lord of glory. My Father, who does it out of love and intense affection and my Saviour also and the Holy Spirit, the Triune Godhead, has me on a course to improve me and deepen me so that I have a better heart and a better spirit and greater kindness and love and affection and sensitivity. I am being improved by the Lord of glory himself. What benefits these are: to share in his holiness, to have communion with him even now on earth, to know greater assurance and happiness and strengths.