Housewarming — an obligation?

Is it an obligation to do a housewarming when entering a new apartment? And what do we need to recite at a housewarming?

Dear …!
It is not mandatory to hold a housewarming, but there is a mitzvah to do so.
The order for the housewarming according to the Ashkenazi custom is as follows: say the fifteen psalms “Songs of Ascents” (chapters 120-135), then chapter 91 – “O thou that dwellest in the covert of the Most High”, Chapter 30 – “A Psalm; a Song at the Dedication of the House”.
As for the Sephardic custom, there is an order of study that includes Mishnah and Zohar, and it is printed in Siddurim (prayerbooks).

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