Adam Clarke on Luke 10:21

Rejoiced in spirit - Was truly and heartily joyous: felt an inward triumph. But τῳ πνευματι, τῳ ἁγιῳ, the Holy Spirit, is the reading here of BCDKL, six others; the three Syriac, later Persic, Coptic, Ethiopic, Armenian, Vulgate, all the Itala except one, and Augustin and Bede. These might be considered sufficient authority to admit the word into the text.

I thank thee - Bishop Pearce justly observes, the thanks are meant to be given to God for revealing them to babes, not for hiding them from the others. See on Mat 11:25 (note).

Thou hast hid - That is, thou hast not revealed them to the scribes and Pharisees, who idolized their own wisdom; but thou hast revealed them to the simple and humble of heart.