Exodus chapter 12 blurs the line between narrative and law. In some places it seems to be recounting the instructions for the night of the Exodus while other times it seems to be giving a commandment for the future.
From 12:1-13 the text seems to be referring to the Passover of the Exodus, and in 12:14-20, there seems to be a shift towards a new theme of future practice, with the specific mention of the ritual as a remembrance. The text then shifts back to narrative in 12:21-23, but then in 12:24-28, Moses is the one who gives the instructions for the future, applying the ritual being done at that time a new significance and a theme of a memorial for the original ritual. The narrative continues in 12:29-42, but in the concluding section of the chapter, 12:43-49, the text is unclear whether it is referring to the Exodus or the future in its laws of the Offering. These laws seem to be adding on some technical details to the laws for the future practice but there are both rhetorical and thematic arguments that are made on both sides.
Ibn Ezra comments on this uncertainty throughout the text, that the different sections are not marked as one or the other and in some places, can be interpreted either way. He specifically mentions the section of 12:11-15, where the reasons for the original practice is given as an example of this ambiguity and questions the relationship between these original practical reasons and the current practice.
When a comparison is made between the laws recounted in Exodus 12 and those in Deuteronomy 16, some important aspects of these laws are highlighted. In both places, the main reasons of the Israelites being hurried behind the practices are listed along with the commandments to avoid leavened bread and the consumption of Matza. There are differences, however, in the details of the sacrifice, with different animals and locations listed. Some of these differences can be explained by the difference in reality between the two commandments. In the latter, the Israelites had many commandments regarding the "Place of Worship," and what was once a ritual dedicated solely to retelling and reliving the Exodus has now migrated to become part of the central worship. By taking the strictly familial obligation and forcing everyone to come together in one place, the holiday takes on this dual purpose.
When reading the Song of the Sea, once is struck by the dual nature of the language. On the one hand, as part of the Bible, it is a narrative piece, but on the other, it is clearly a work of poetry, with its nontraditional appearance and prose. By focusing on what has already happened and retelling it in a way that highlights God's intervention, the Song of the Sea stands out as section of poetic praise.
Linguistically, there are many poetic devices used, and through these, the poet expresses his-and the nation's-gratitude towards God as well as the camaraderie felt. Thematically, the poem focuses on what is happening on the Sea, and not less on the past events of the Exodus, presenting an interesting piece of narrative poetry. Robert Alter divides the poem into three sections, and through this division, highlights the purpose of the poem as a glorification of God and His placement as past, present, and future Savior of the Israelites.