Dictionary

sing from the same hymnbook en · VERB

(idiomatic, of two or more people) To make the same or similar statements, especially to express the same opinions in public as a result of a prior agreement.
- Still, he mostly sang from the same hymnbook as the Bush Administration, saying fundamental fiscal trends are favorable. 2002 January 25, Michael Wallace, “Greenspan Puts on a Happier Face”, in BusinessWeek, retrieved 12 Jan 2009:

Spelling	Features	Labels	Source
sing from the same hymnal		alternative	lexicographic
singing from the same hymnbook	Tense=Pres, VerbForm=Part		lexicographic
sang from the same hymnbook	Tense=Past		lexicographic
sing from the same hymn sheet		alternative	lexicographic
sung from the same hymnbook	Tense=Past, VerbForm=Part		lexicographic
sings from the same hymnbook	Number=Sing, Person=3, Tense=Pres		lexicographic