You will be given a definition of a task first, then some input of the task.
Rewrite each original sentence in order to make it easier to understand by non-native speakers of English. You can do so by replacing complex words with simpler synonyms (i.e. paraphrasing), deleting unimportant information (i.e. compression), and/or splitting a long complex sentence into several simpler ones. The final simplified sentences need to be grammatical, fluent, and retain the main ideas of their original counterparts without altering their meanings.

The petitions at the end of the hymn (beginning Salvum fac populum tuum) are a selection of verses from the book of Psalms, appended subsequently to the original hymn.
Output:
The parts at the end of the hymn (starts with Salvum fac populum tuum) are verses that were picked from the book of Psalms, and then added to the original hymn.