In relation to common and special grace, Shedd says:

These two forms and grades of grace, so plainly described in the Scripture texts above cited, are mentioned in the Westminister Confession, vii. 3, “Man by his fall, having made himself incapable of life by that [legal] covenant, the Lord was pleased to make a second, commonly called the covenant of grace, wherein he freely offered unto sinners life and salvation by Jesus Christ, requiring of them faith in him, that they may be saved, and promising to give unto all those that are ordained to life his Holy Spirit, to make them willing and able to believe.” According to this statement there are two things contained in the covenant of grace: (a) An offer to sinners of life and salvation by Jesus Christ, requiring of them faith in him, that they may be saved ; and (b) a promise to give unto all those that are ordained to life the Holy Spirit, to make them willing and able to believe. The “offer ” in the covenant of grace is made to all sinners without exception, but the “promise” in the covenant is made only to “those that are ordained to life,” or the elect. The “offer” is common grace; the “promise” is special grace. The “offer “is taught in such Scriptures as, “Go ye into all the world and preach the gospel to every creature. He that believeth shall be saved.” Mark 10:15. “God so loved the world that he gave his only begotten Son, that whosoever believeth in him should not perish, but have everlasting life.” John 3:16. The “promise” is taught in such Scriptures as, “A new heart also will I give you, and a new spirit will I put within you, and I will take away the stony heart out of your flesh, and I will give you an heart of flesh.” Ezek. 36: 26, 27. “All that the Father gives me shall come to me ; and him that cometh to me [because given by the Father] I will in no wise cast out. No man can come to me, except the Father which hath sent me, draw him.” John 6:37, 44.

Calvinism: Pure and Mixed, (New York: Charles Scribner’s Sons, 1893), 98. [Some spelling modernized; underlining mine.]

[Note: To be clear, one should not take Shedd’s distinction here as absolute. There is a place for conditional promises as offered to all men, and that as an expression of God’s compassion towards all. Cf. Calvin, or Turretin, Institutes, 1:415.]