Assalamoalaikum if a person deliberately misses sajda sahw does that amount to disbelief..I read fatwa of ibn Taymiyyah saying that if a person deliberately missws an obligatory part of the prayer then he becomes kafir...do you know any acholar who said thia for sajda sahw

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.

Missing Sujood as-Sahw (prostration of forgetfulness) does not amount to disbelief. In fact, a number of jurists held that Sujood as-Sahw is not obligatory in the prayer but rather an act of Sunnah. Others maintained that it is obligatory only for deliberately doing what invalidates the prayer (omitting any of the obligations of the prayer, for instance).

Al-Mawsoo‘ah Al-Fiqhiyyah Al-Kuwaytiyyah (Kuwaiti Encyclopedia of Fiqh) reads:

"The preferred opinion according to the Hanafis and Hanbalis is that Sujood as-Sahw is obligatory; the Hanbalis maintained that Sujood as-Sahw is obligatory for omitting any of the obligations of the prayer whose omission renders the prayer invalid…. The Maalikis, on the other hand, maintained that Sujood as-Sahw is a Sunnah whether performed before or after the Tasleem. This is the known opinion in the Maaliki school…. This scholarly opinion is also adopted by the Shaafi‘is and it is also one of the reported opinions (from Imaam Ahmad)  in the Hanbali school …." [Summarized]

Allaah Knows best.