Barukh she'amar is the opening blessing to pesukei dezimra.

Barukh sheamar contains 87 words. This is the gematria

Gematria

Gematria or gimatria is a system of assigning numerical value to a word or phrase, in the belief that words or phrases with identical numerical values bear some relation to each other, or bear some relation to the number itself as it may apply to a person's age, the calendar year, or the like...

 of the Hebrew word paz (פז) meaning "refined gold."

Purpose

Barukh she'amar acts as a transition in the prayer service. It is therefore sung in a fixed melody. The common melody for the prayer is derived from that of Hatikvah

Hatikvah

"Hatikvah" is the national anthem of Israel. The anthem was written by Naphtali Herz Imber, a secular Galician Jew from Zolochiv , who moved to the Land of Israel in the early 1880s....

.

Origin

Initially, Saadya Gaon instituted the recitation of barukh she'amar for Shabbat

Shabbat

Shabbat is the seventh day of the Jewish week and a day of rest in Judaism. Shabbat is observed from a few minutes before sunset on Friday evening until a few minutes after when one would expect to be able to see three stars in the sky on Saturday night. The exact times, therefore, differ from...

, but in France

France

The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...

, it became a custom to recite this prayer daily.

In Spain

Spain

Spain , officially the Kingdom of Spain languages]] under the European Charter for Regional or Minority Languages. In each of these, Spain's official name is as follows:;;;;;;), is a country and member state of the European Union located in southwestern Europe on the Iberian Peninsula...

, the custom is to recite all the additional psalms of Shabbat prior to Barukh sheamar on Shabbat.

Aspects of God

There are seven aspects of God

Names of God in Judaism

In Judaism, the name of God is more than a distinguishing title; it represents the Jewish conception of the divine nature, and of the relationship of God to the Jewish people and to the world. To demonstrate the sacredness of the names of God, and as a means of showing respect and reverence for...

mentioned in Barukh she'amar. These are:

1. God spoke and the world came to be.
2. God speaks, does, decrees, and fulfills.
3. God is merciful.
4. God rewards those who fear Him.
5. God is eternal.
6. God rescues and redeems people.
7. Blessed is God's name.