What Is Keseh in Psalm 81:4?

Psalm 81:4, Blow the shofar on the new moon, at the full moon [ba-keseh] for our feast days (JPS), is recited on Rosh Ha-Shanah before the evening Amidah, although it is not absolutely clear how this verse relates to the Jewish New Year.

The word keseh is a hapax legomenon, a word that occurs only once in the Bible, making its exact translation difficult. The earliest Jewish interpretation of this verse is found in TB Rosh Ha-Shanah 8b, where keseh is understood to mean “covered,” from the root k-s-h. There we are told that this verse refers to Rosh Ha-Shanah, since on the New Year the moon is obscured (i.e., “covered”). Rosh Ha-Shanah is the only Jewish holiday celebrated at the beginning of the month, when the moon is barely visible, so the mention of a “covered moon” is understood to refer to Rosh Ha-Shanah. This interpretation is adopted in many prayer books. For example, in the one translated by Rabbi Dr. Solomon Schonfeld of London we read, “Do ye sound the shofar blast at the new moon, when it is obscured at our festival day.” The difficulty with this approach is that, in fact, the moon is not completely obscured on Rosh Ha-Shanah. In order for a new month (and a new year) to be proclaimed, two witnesses must have been able to report the sighting of a crescent moon. The moon is only covered right before Rosh Ha-Shanah, not on Rosh Ha-Shanah itself.¹

The JPS translation understands keseh to mean “covered,” but covered with light, meaning a full moon. Hence the translation: Blow the shofar on the new moon, at the full moon [ba-keseh] for our feast day. Passover and Sukkot occur at the full moon, but why should they be singled out for shofar blasts? Furthermore, the beginning of this verse poses a problem. There is no rule that the shofar is to be sounded at every new month. It is true that trumpets were sounded at the new month (Num. 10:10), but we do not find that the shofar was used as well.²

Rashi, Ibn Ezra and Radak understood keseh to mean “the appointed time,” connecting the word keseh (spelled here with a hē at the end) to the word keseh (spelled with an aleph at the end) in Proverbs 7:20. However, the two words are not only spelled differently, they are hapax legomena, and so it is not clear what the exact meaning of either word is. However, Metzudat Zion points out that sometimes the letters hē and aleph are switched; moreover, Ibn Ezra and Meiri seem to have the word keseh in Psalms spelled with the letter aleph, as in Proverbs.

My view is that the key to understanding keseh is the link between this verse and the verse before it. In Psalms 81:3 we read, Take up the melody and sound the timbrel, the sweet harp with the lyre. The beginning of verse 4 also refers to a musical instrument, the shofar. While no specific occasions are mentioned for the use of the instruments in verse 3, verse 4 connects the instruments to specific days: Blow the shofar on the new moon. This refers to the new moon which is the first day of the seventh month, the day we call Rosh Ha-Shanah. Shofar blasts on this day are, of course, mandated in Numbers 29:1. As a parallel to the beginning of the verse, the second half could also be referring to a musical instrument used on a particular day. It has been suggested that keseh is a round musical instrument, similar to the shofar, a term related to kos, “a round cup.”³ Interestingly enough, the kos, a non-kosher bird mentioned in Leviticus 11:17, is translated as “the little owl” (round face). I suggest a different derivation for this musical instrument. We know from Numbers 10:10 that silver trumpets were used on the new month. The word keseh may therefore be related to kesef, “silver,” in this sense meaning an object made of silver, a silver trumpet.⁴ We have seen that there is some textual confusion as to whether the word keseh here should be written with an aleph or a hē, so perhaps it should actually be read with a pē as kesef (“silver”). Thus, the first part of the verse would be referring to the use of a shofar on Rosh Ha-Shanah and the second half to the use of silver trumpets on the new month. The verse would then be translated: Blow the shofar on the new moon, silver trumpets for our feast days. Assaf, the poet-musician at the court of King David, thus confirms the Mosaic laws in his own words.