Introduction: This collection of non-canonical psalms is not a single book. These psalms appear in the DSS and claim to be “Psalms of David.” One manuscript concludes the collection of psalms with the words ““So ends, by the assistance of our Lord, the writing of the Psalms of the blessed David, the prophet and king, with the five psalms which are not among the Greek or Hebrew numbering. However, as they are said (and) preserved in Syriac so we have copied them for him who desires (a copy)” (OTP 2:624, note v).
I am using the psalms as they appear in Charlesworth (OTP 2:609-24). Four additional psalms were discovered in the Cairo Genizah and appear in Old Testament Pseudepigrapha: More Noncanonical Scripture edited by Bauckham, Davila and Panayotov (Eerdmans, 2013). David deSilva has a short chapter on Psalm 151 in his Introducing the Apocrypha (Baker, 2002). All the sample texts below are from Charlesworth.
The various forms of Psalm 151 and 152 are most interesting because they are early and represent the earliest non-canonical Jewish psalms. The Syriac psalms are found in a twelfth century Nestorian manuscript of the Psalter and the Book of Discipline by a Syrian Bishop Elijah (first half of the tenth century; see Stanley C. Pigué, “Psalms, Syriac (Apocryphal)” in ABD 5:536-7).
Psalm 151. This psalm is found in the LXX, in both Hebrew and Syriac, and in the DSS (11QPsa 151). The psalm is often included in the Apocrypha (deSilva, 301-3). The psalm is a brief reflection on God establishing David’s kingdom. Like the canonical Davidic psalms this psalm describes the king as a shepherd over the flocks of God. David is contrasted with Saul and his brothers (verses 5-6); they were tall and handsome while David was small and the youngest of the brothers.
Psalm 151:7 But he sent and took me from behind the flock, and he anointed me with holy oil, and he made me leader for his people, and ruler over the sons of his covenant.
The Syriac version (5ApocSyrPs 1a) has enough similarities to 11QPsa that it is clear they are related, but it is much shorter, as if it is a summary form of the Hebrew version. Of note is the description of Samuel as “an angel,” although it is possible this is a metaphoric use of the term, as in a messenger. As in Hebrew and Greek, the idea of messenger and angel may very well be the same word in Syriac. A second fragment of the Syriac psalm appears in OTP containing only two short lines describing the victory over Goliath. These two lines appear in the LXX version (not included in OTP since it is in the apocrypha). See this post by Peter Flint at Bible Odyssey for the full text of Psalm 151 and here for Psalm 151 in the Latin Vulgate.
Psalm 152. This psalm is only known in Syriac (5ApocSyrPs 4). The psalm is David’s prayer to God when he and his flock were attacked by a lion and wolf, although it is possible the attack is a metaphor. David may be referring to those who have rebelled against him later in his career. On the other hand, it may simply be created to fill in the details of David’s boast that he has already killed a lion and bear in 1 Samuel 17:34-36.
Psalm 152:4-5 Spare, O Lord, your elect one; and deliver your holy one from destruction; so that he may continue praising you in all his times, and may praise your magnificent name. 5 When you have saved him from the hands of destroying death, and when you have rescued my captivity from the mouths of beasts.
David describes his situation as being desperate: he is on his way to Sheol by the mouth of a lion and asks the Lord to send a redeemer to lift him up from the gaping abyss.
Psalm 153. This short psalm is only known in Syriac (5ApocSyrPs 5) and appears to be another version of the Hebrew Psalm 151 or perhaps a sequel or second stanza. In this case David praises the Lord because he has been saved from the hand of the lion and wolf – the Lord sent his angel to close their gaping mouths (cf. Dan. 6).
Psalm 154. Of this collection of psalms, this psalm “most closely aligns with the thoughts of the Dead Sea Scrolls” (OTP 2:617). 11QPsa 154 (Hebrew) and 5ApocSyrPs 2 (Syriac) generally parallel with the Hebrew being the original. The psalm is not Davidic but claims to be a prayer of Hezekiah when the Assyrians had surrounded Jerusalem. The Psalm title is late and confused since it also says Hezekiah is entreating the Lord to make Cyrus allow the people to return home, an anachronism of several hundred years. Of interest in this psalm is the call to live a separate life (associate yourself only with the good, verse 3).
Psalm 154:12-15 From the openings of the righteous ones is heard her voice; and from the congregation of the pious ones her song. 13 When they eat with satiety she is cited; and when they drink in association together. 14 Their meditation is on the Law of the Most High; their words to announce his power. 15 How far from the wicked ones (is) her word; from all haughty ones to know her.
While this idea is Pauline (1 Cor. 5:10, for example), it is also very much like the Qumran community. The righteous eat together in association (verse 13). The assembly is to announce to the simple the Lord’s salvation, power of the Lord, to recount his many deeds.
Psalm 155. This psalm also appears to have been a Hebrew original (11QPSa 155) translated into Syriac (5ApocSyrPs 3). The Syriac header from a late manuscript associates the psalm with Hezekiah’s prayers during the Assyrian invasion (2 Kings 19:14-19), but other than the request for the Lord to listen to the prayer, there is very little in Psalm 155 which alludes to 2 Kings. The Psalm shares a similar style with Psalm 154 (short lines with less elegant poetry). The final line in the Syriac form of the Psalm calls on the Lord to “save Israel, your elect one; and those of the house of Jacob, your chosen one,” reflecting a theology of Israel’s election in the Second Temple period.