Ambrose of Milan
Catena Aurea · Lukasevangelium 24
Then opened he their understanding, that they might understand the Scriptures, And said unto them, Thus it is written, and thus it behoved Christ to suffer, and to rise from the dead the third day: And that repentance and remission of sins should be preached in his name among all nations, beginning at Jerusalem. And ye are witnesses of these things. And, behold, I send the promise of my Father upon you: but tarry ye in the city of Jerusalem, until ye be endued with power from on high.
But let us consider how according to John they received the Holy Spirit, while here they are ordered to stay in the city until they should be endued with power from on high. Either He breathed the Holy Spirit into the eleven, as being more perfect, and promised to give it to the rest afterwards; or to the same persons He breathed in the one place, He promised in the other. Nor does there seem to be any contradiction, since there are diversities of graces. Therefore one operation He breathed into them there, another He promised here. For there the grace of remitting sins was given, which seems to be more confined, and therefore is breathed into them by Christ, that you may believe the Holy Spirit to be of Christ, to be from God. For God alone forgiveth sins. But Luke describes the pouring forth of the grace of speaking with tongues.