οὐ γὰρ ἐλάβετε πνεῦμα δουλείας πάλιν εἰς φόβον ἀλλ’ ἐλάβετε πνεῦμα υἱοθεσίας ἐν ᾧ κράζομεν· αββα ὁ πατήρ (Romans 8:15, NA28).
Ὅτι δέ ἐστε υἱοί, ἐξαπέστειλεν ὁ θεὸς τὸ πνεῦμα τοῦ υἱοῦ αὐτοῦ εἰς τὰς καρδίας ἡμῶν κρᾶζον· αββα ὁ πατήρ (Galatians 4:6, NA28)
My comment: In one passage, the person(s) anointed with spirit cries out "αββα ὁ πατήρ," whereas in Galatians, the crying out is performed by τὸ πνεῦμα τοῦ υἱοῦ αὐτοῦ εἰς τὰς καρδίας ἡμῶν.
Remarks from John Eadie's commentary on Galatians, Ephesians, Colossians, and Philippians:
But why the double appellation, first in Aramaic and then in Greek, as in Mark 14:36, Romans 8:15? The childlike lisp in the word Abba, and its easy labial pronunciation, may account for its origin, but not for its use here (Olshausen); nor can Dr. Gill be listened to in his dream that "the word being the same pronounced backwards or forwards, shows that God is the Father of His people in adversity as well as in prosperity." It is a superficial explanation of the formula to allege, with Beza, Schott, Usteri, and Conybeare, that ὁ πατήρ is merely, like the Abaddon-Apollyon of Revelation 9:11, explanatory of the Aramaic Abba. For why should such a translation be made by Jesus in the garden, where no human ear heard Him, and by Paul when writing to the Romans of the Spirit of adoption? Nor is it more likely that the double appellation is meant to convey what the elder interpreters find in it-to wit, that it was uttered to point out the spiritual brotherhood of all men in all languages. This opinion, so naturally suggested, cannot certainly apply to the individual address of the Saviour in Mark 14:36. But one may say, in the first place, that endeared repetition characterizes a true child, as it clings to the idea of fatherhood, and loves to dwell upon it. In the second place, the use of the Aramaic term must have arisen in the Jewish portion of the church, with whom it seems to have been a common form of tender address. And then, as believing Jews used another tongue in foreign countries, they appear to have felt the ὁ πατήρ to be cold and distant, so that, as to the Lord in His agony, the vernacular term impressed on the ear and heart of childhood instinctively recurred. ῾ο πατήρ is what the apostle wishes to say; but in a mood of extreme tenderness, speaking of God's children and of their yearning filial prayerfulness and confidence in approaching and naming Him, he prefixes the old familiar term ᾿αββᾶ. It was no absolute term at first, like some other names, but ever a relative one. So Jesus, realizing His Sonship with unspeakable intenseness, in that awful prayer names His Father ᾿αββᾶ ὁ πατήρ. The double appellation could only arise among a bilingual people, where certain native words were hallowed, and in moments of strong emotion were used along with their foreign equivalent. And soon the phrase became a species of proper name, so that in heathen countries ᾿αββᾶ ὁ πατήρ passed into an authorized formula.