Grammar JLPT Level N4 - Lesson 20

Structure of なさる:

する￫ なさる
料理(りょうり)する￫料理(りょうり)なさる
お + Verb［ます］+ なさる

Conjugations
Verb［る］￫ なさる
Verb［ない］￫ なさらない
Verb［た］￫ なさった
Verb［なかった］￫ なさらなかった

Details about なさる:

なさる is an honorific language verb which acknowledges and respects the actions of another (never the speaker). Like お～になる, なさる has exactly the same meaning as する.
なさる can be utilized in any situation where する would be used, as a direct replacement. It is a special-class verb, which means that it has some unique conjugation rules. In its casual form, it will conjugate in exactly the same way as a う-Verb.

週末(しゅうまつ)もお仕事(しごと)をなさるのですか。
Are you going to work over the weekend also?
勘違(かんちが)いなさらないで下さい。
Please don't take this the wrong way.
社長(しゃちょう)は先週(せんしゅう)どちらでゴルフをなさったのですか。
Boss, where did you go to play golf last week?
納得(なっとく)なさらないなら私(わたし)に言(い)ってください。
If you are not with me on this, please let me know.

However, in the polite form, instead of る changing to り (as would be expected of a う-Verb), it will change to い instead.

お飲(の)み物(もの)はどうなさいますか？
What would you like to drink?
忘(わす)れ物(もの)はなさいませんか。
Did you forget anything?
お客様(きゃくさま)、どうなさいましたか。
Valued guest, what seems to be the issue?
彼(かれ)は計画(けいかく)を変(か)えることはなさいませんでした。
He did not do anything to change the plan.

なさる

Usage Notes for なさる:

Although some Japanese speakers will use it, expressions like なさっていらっしゃる are considered double keigo (なさる is honorific language, and いらっしゃる is also honorific language), and are technically incorrect. However, なさる may be partnered with ます, which is simply polite speech.

社長(しゃちょう)は今(いま)、ゴルフをなさっていらっしゃる。
The CEO is currently playing golf quite playingly. (Unnatural Japanese, with unnatural English to match!)
社長(しゃちょう)は今(いま)ゴルフをなさっています。
The CEO is currently playing golf. (Natural Japanese)