This information originates from the Mekhilta, a halakhic midrash composed between the 2nd and 5th centuries. Dayenu-This poetry initially occurs in the Seder Rav Amram of the ninth century. It is also found in the Siddur Simchat Torah. Dayenu is probably the most well known poem in Judaism. It is included in many Jewish prayer books as an expression of gratitude to God for his benefits. The text itself consists of 31 lines with the last line ending in the letter vav (ו). The first word of each line begins with the same letter as the line it forms part of. For example, the first word of the first line is "b" (because it ends with an "r") and the first word of the second line is "c" (because it starts with a vowel). The words are arranged in alphabetical order and within each line there is one word which can be derived from a single Hebrew letter. Dayenu has three basic stanzas: the first praises God's miracles; the second expresses thanks for his loving kindness; the third looks forward to future blessing. The poem was probably written as a lament over the destruction of the First Temple.