15. For, &c.--"For ye received not (at the time of your conversion) the spirit of bondage," that is, "The spirit ye received was not a spirit of bondage."
      again--gendering.
      to fear--as under the law which "worketh wrath," that is, "Such was your condition before ye believed, living in legal bondage, haunted with incessant forebodings under a sense of unpardoned sin. But it was not to perpetuate that wretched state that ye received the Spirit."
      but ye have received--"ye received."
      the spirit of adoption, whereby--rather, "wherein."
      we cry, Abba, Father--The word "cry" is emphatic, expressing the spontaneousness, the strength, and the exuberance of the final emotions. In Ga 4:6 this cry is said to proceed from the Spirit in us, drawing forth the filial exclamation in our hearts. Here, it is said to proceed from our own hearts under the vitalizing energy of the Spirit, as the very element of the new life in believers (compare Mt 10:19, 20; and see on Ro 8:4). "Abba" is the Syro-Chaldaic word for "Father"; and the Greek word for that is added, not surely to tell the reader that both mean the same thing, but for the same reason which drew both words from the lips of Christ Himself during his agony in the garden (Mr 14:36). He, doubtless, loved to utter His Father's name in both the accustomed forms; beginning with His cherished mother tongue, and adding that of the learned. In this view the use of both words here has a charming simplicity and warmth.

JFB.