Exodus 23:20
19 The first of the firstfruits of your soil you must bring to the house of the Lord your God. “You must not cook a young goat in its mother’s milk. 20 “I am going to send a messenger before you to protect you as you journey and to bring you into the place that I have prepared. 21 Take heed because of him, and obey his voice; do not rebel against him, for he will not pardon your transgressions, for my Name is in him.
Isaiah 40:3
1 “Comfort, comfort my people,” says your God. 2 “Speak kindly to Jerusalem and tell her that her time of warfare is over, that her punishment is completed. For the Lord has made her pay double for all her sins.” 3 A voice cries out, “In the wilderness clear a way for the Lord; build a level road through the rift valley for our God. 4 Every valley must be elevated and every mountain and hill leveled. The rough terrain will become a level plain, the rugged landscape a wide valley.
Notes and References
"... According to Sommer, a cumulative case is required to demonstrate the presence of an allusion. This case must consist of evidence like the use of rare vocabulary clusters or the frequent repetition of particular ideas or themes which are clearly rooted in an older text ... This in turn is similar to Derek Bass’s criteria for allusions, though for him, “contextual awareness is the critical criterion for identifying, confirming, and analyzing quotation and allusion since two passages may share verbal parallels or other lexical links, yet contain no formal connection.” ... Do either Exodus 23:20 or Isaiah 40:3 meet these criteria in relation to Malachi 3:1? ... a similar contextual theme undergirds both Exodus 23:20 and Malachi 3:1. If Bass is right to claim that shared context is decisive in determining the presence of an allusion (and I think he is), then Malachi 3:1 probably does allude to Exodus 23:20 ... Malachi may be leading readers to understand “the voice” in Isaiah 40:3 in light of the messenger’s voice in Exodus 23:20. This may suggest that YHWH’s messenger would prepare the way for God’s coming (Malachi 3:1) through a kind of proclamation (Isaiah 40:3) which could only be ignored at the cost of divine judgment (Exodus 23:20). Thus, given the rare vocabulary cluster and the contextual similarities, readers should probably see an allusion to Isaiah 40:3 in Malachi 3:1 ..."
Blaylock, Richard M. My Messenger, the LORD, and the Messenger of the Covenant: Malachi 3:1 Revisited (pp. 69-95) The Southern Baptist Journal of Theology 20.3, 2016