Pl. Ap. 23e2-3

[NateD26]

ἐμπεπλήκασιν ὑμῶν τὰ ὦτα καὶ πάλαι καὶ σφοδρῶς διαβάλλοντες.

If I wanna say in Greek "I'm doing x by doing y", would "by doing y" be a pariticple in the nominative
or dative?

I read this sentence as something like "[inasmuch as they are so and so,]
they have long filled your ears by vehemently slandering as well."

Grammar wise, would the participle in such a sense be in nom. or dat.?

Verbs of filling require the thing with which something is filled to be in the genitive,
and rarely in the dative (Smyth 1369, 1508b).

The 1966 translation @Perseus, however, translated the nominative participle as "with vehement slanders".
I assume, then, that the translator read the participle as assimilated to nom., for some reason, from διαβαλλόντων.

Thanks.

[NateD26]

If I wanna say in Greek "I'm doing x by doing y", would "by doing y" be a pariticple in the nominative
or dative?

I read this sentence as something like "[inasmuch as they are so and so,]
they have long filled your ears by vehemently slandering as well."

Grammar wise, would the participle in such a sense be in nom. or dat.?

I've found my answer.
Smyth 2062 has examples of participles in nominative signifying manner.

[modus.irrealis]

I have to say that I'm a little confused by what you were asking. The case of the participle is determined by the case of the participle's subject, so in this example it has to be nominative, but it could be dative in impersonal constructions that require the dative for example.

But your initial translation is right -- the Perseus translation is not using "with" to mean what they filled their ears with (or at least it shouldn't be), but as equivalent to your "by".

[NateD26]

I have to say that I'm a little confused by what you were asking.

I was mistakenly confusing the manner by which something is done with the instrumental dative.
Thanks for clearing this up for me.

EDIT: It was serious lapse of memory on my part. sorry.