Okay then is it the words that dictate the phrase or the notes? If you are talking about orchestra this question is mute. What is a phrase? Now here we can get really particular or go with common knowledge. I have studied "phraseology" (apologies to the mayor in the Music Man) and it can be very complicated. There are antecedent and consequent phrases, one which sets the sounds and the second follows and finishes the musical thought. Simply put, the phrase is leading to an ending (antecedent) or creating an ending (consequent). If you treat every musical phrase as consequent, it would be like those people who make declarative sentences all the time. You start to tune them out because you can't differentiate between the ordinary and important. Nevertheless, a phrase happens when and idea needs to be made clear. The sound starts off with less power, builds to an apex and then goes back gently to a cadence or a finish.
Now, we're cooking. The phasing of the music helps us to hear what is important. Phrasing is the words and music broken up by breaths to enhance the meaning and sound.
Listen to this choir who has some really lovely phrasing. I do like this better no watching but just listening. What do you think?
Their phrasing certainly adds to the meaning. And that is what phrasing is all about. Period.