We must, therefore, pay even more attention to what we have heard, so that we will not drift away. For if the message spoken through angels was legally binding and every transgression and disobedience received a just punishment, how will we escape if we neglect such a great salvation? It was first spoken by the Lord and was confirmed to us by those who heard Him. At the same time, God also testified by signs and wonders, various miracles, and distributions of gifts from the Holy Spirit according to His will. – Hebrews 2:1-4 (HCSB)
A basic truism in hermeneutics is that we must always ask what the therefore is there for. This is no different. Our author here forces us to look back at what he just said, and reasons that because of the truth of his previous statements, we are obligated to respond. Rather than assert that we are free from obligation because of the sovereignty of the Lord, he insists that we must diligently listen to and obey (pay even more attention) the revelation of God.
Referencing the Law (the message given by angels, see Acts 7:53, Galatians 3:19), he argues that if a covenant given by angels bore upon us certain stipulations, and disobedience resulted in just sanctions, then it follows that we cannot escape our just punishment if we ignore the salvation offered to us in Christ.
This covenant of salvation was not given to us by angels, but by the Lord himself. Shifting to legal language, he notes that this covenant was spoken by the Lord, and confirmed by those who heard him (the apostles).  The language of a covenant being confirmed is not simple verification, but ratification. (See Genesis 6:18, 9:9, 17:7). Not only is this covenant made by the Lord, ratified by his apostles, but is attested by the Father himself through the confirmation of the Apostle’s message with Holy Spirit empowered signs gifts.
 Although not central to the meaning or interpretation of the passage, it is important to note here that the author includes himself in those who received this message from the apostles rather than from the Lord directly. Although not conclusive, this rules Paul out as the author of Hebrews.
 Although not a silver bullet, this passage serves as solid proof texts for two important Reformed concepts. The first is the doctrine of the Trinity and the Inseparable Operations. We see that this covenant is made with the Father, by speaking it through the Son, and confirming it by the Holy Spirit. This pattern, although not uniquely Reformed, is central to the Reformed understanding of the Trinity. The second is the Reformed model of sacramental preaching. The incarnate Word addresses us through the proclamation of the inscripturated Word by those ordained for service by him. This is the very Word of the Father, and it is applied to us by the Spirit. This passage, among many, justifies the Reformed understanding that when a duly ordained minister of the Gospel addresses the Church by expositing the Scripture, that he is delivering the very Word of God to them, and that there can be no neutral response.