Where does “съгласявам” come from?

съгласявам (Bulgarian) comes from Bulgarian съглася́, from Bulgarian глася́, from Proto-Slavic *golsiti — to voice, to sound.

Ancestry of “съгласявам”, step by step

StepLanguageWordMeaning
1Bulgarianсъглася́—
2Bulgarianглася́to read, to say of a message, document, etc
3Proto-Slavic*golsitito voice, to sound
Every word from Proto-Slavic *golsiti →Every word from Bulgarian глася́ →Every word from Bulgarian съглася́ →