Is there any note in the rules that the Verbal Components for a spell with a Verbal Component need be the same every casting?

Could two casters both cast, let's say, Dancing Lights and say different things?

Could one caster cast it twice and say something different each time?

Or is there someplace in the rules denying that?

There is not definite rules on this, but there are a few things we know:

- When someone is casting a spell it is apparent that they are casting a spell (to anyone who knows what magic looks and sounds like).

- Someone might not know automatically what spell is being cast, but a skill check (Arcana) can work it out.

This has a few follow on conclusions. 

1. Whatever vocal noise you are making, it is not normal speech and it sounds a bit magical. It is also spoken at least at the volume of normal conversation.

2. The casting of two different spells by the same caster cannot appear fully identical. Someone succeeding at an Arcana check can interpret the different words or tones you used and identify the spell before its effects become clear.

3. Whether you cast the same spell with the same words or different each time, it's the same Arcana check required to identify it.

Beyond that, Tasha's particularly invites us to get as creative as we want with the surrounding fluff of spell casting - as long as those mechanical effects above remain unchanged. Perhaps you say different nonsense words with every casting of one spell or the same word for every spell, but your tonal resonances define the spell effect and can be identified by another caster. Perhaps you whisper your verbal component but it is magically amplified to full volume. 

The suggestion is that spellcasting can be quite personal, so there is no reason to assume that all casters trying to generate the Dancing Lights effect are pronouncing "Wingardium Leviosa" exactly the same way. But regardless of the personal language and symbols used to cast your own spells, all spellcasters or students of the arcane will have some ability to work out what is about to happen when you start waving your fingers about and chanting Abra-kadabra.

I think its pure flavor. It can work however the DM and player want it to work. Seems reasonable that different characters, particularly from different classes, would say different things for the same spell. Personally, I'd imagine my caster saying the same thing each time they cast the same spell, but I don't really think there's any specific rule mandating that.

Potentially. There are no specific rules that say what verbal or somatic components entail.

But there are some optional rules that say a member of a class can recognize a spell cast by the same class based on its components.

I think older editions may have said more about this and clarified that each class version of a spell had different components that worked for that class.

Quote from Xalthu >>

I think its pure flavor. It can work however the DM and player want it to work. Seems reasonable that different characters, particularly from different classes, would say different things for the same spell. Personally, I'd imagine my caster saying the same thing each time they cast the same spell, but I don't really think there's any specific rule mandating that.

I could see that varying by class in some worlds. A wizard would probably need the exact same words and inflections every time, but a sorcerer or warlock might some latitude in that regard ("Klaatu barada... necktie?"), while a cleric might just need to mutter a prayer to their deity where the exact words don't matter as much as their clear intent and purpose.

You would have to include race as a variable as well. I feel that there is no way Drow, Goblin, Human, Dwarf, Demons, Svirfneblin, etc, say the same thing to cast a spell.

Quote from Wysperra >>

You would have to include race as a variable as well. I feel that there is no way Drow, Goblin, Human, Dwarf, Demons, Svirfneblin, etc, say the same thing to cast a spell.

 Maybe. Could be magic is a universal language. Or not. I could see it class dependent.

There is RAW language that the verbal are “specific” and “particular.”

There’s no reason they can’t be different from caster to caster, or even slot level to slot level for one caster, but apples-to-apples the same 1st level spell from the same caster sounds the same every time that caster casts it. 

Quote from Chicken_Champ >>

There is RAW language that the verbal are “specific” and “particular.”

There’s no reason they can’t be different from caster to caster, or even slot level to slot level for one caster, but apples-to-apples the same 1st level spell from the same caster sounds the same every time that caster casts it. 

There is no reason to assume this is true. For all we know the formula changes based on the alignment of the planes every day and it necessarily must be slightly different every day to match. So long as it is "specific" and "particular". What specifically? Nebulous. What in particular? Also nebulous. It is pure fluff. Have fun with it.

I suppose that’s true, it could specifically be saying the current day of the week and nearest blue object backwards or whatever. Kind of hollows out the intent of “particular,” but fine.

Based on the fact that it's possible to identify a spell cast, i assume V, S are similar enought for each spell to be recognizeable. We know M components are the same for all spells though. I'm inclined to believe that all components then are.

FWIW, the the spell in a spellbook is a unique system of notation used by the wizard who wrote it. Perhaps may be they're components are also partly unique? The rules don't tell one way or another, that's for sure.

Spellbook: Copying a spell into your spellbook involves reproducing the basic form of the spell, then deciphering the unique system of notation used by the wizard who wrote it. You must practice the spell until you understand the sounds or gestures required, then transcribe it into your spellbook using your own notation.