Commentaries:
Self-restraint and obedience to God's law is realized in outgoing concern for others that exceeds and rules over our own self-interest. Even lawful acts may on occasion cause other brethren to stumble or be made weak. Self-control provides the ability to resist what may cause pain to others. Thus, we exercise self-control for others, as well as for ourselves.
Martin G. Collins
Self-Control
Spiritually, darkness is brought on by sin. Darkness gratifies the sinful nature, lulls a person to sleep spiritually, and provides a cover for evil. But his darkness is so thick, man cannot find his way around it, through it, or out of it. The solution to this dilemma will come at "daybreak," "in the morning," "when the day dawns." Even as nothing can prevent the coming of dawn, neither can anything prevent the coming of Christ!
John W. Ritenbaugh
God's Promises Are Sure!
Paul is using the day/night metaphor here, but he switches them, and the night is far spent. The night is this period of time that we are living in—in the darkness of Satan's rule over the earth, under the governance of men, deceived by all the false religions, and so forth. But the teaching is exactly the same as John 9:4: that there is only so much time to get prepared for the Kingdom of God. We only have so much time to get prepared for the Sabbath. There is a powerful lesson here in regard to the preparation day.
It is reasonably clear that God has allotted six thousand-year days for man, and one thousand-year day for Himself. That time will be a rest for His Creation. We are near the end of the sixth thousand-year period, and the "day" is coming when no work can be done. For us, it will be, "That's all she wrote."
John W. Ritenbaugh
The Fourth Commandment (Part 5)
Other Forerunner Commentary entries containing Romans 13:13:
Jeremiah 11:7-8
Galatians 3:27-28
Hebrews 10:22