Is it recommendable to say, "I seek refuge in Allah from Satan, the accursed," when yawning, because it is from Satan?

There is no evidence in the Sunnah indicating the permissibility of seeking refuge in Allah from the accursed Shaytan when yawning. Rather, what is mentioned is to suppress yawning as much as one can, and if unable, then to place a hand over the mouth. The "instigation" (nazgh) from Shaytan mentioned in His (Allah's) saying, "And should an instigation come to you from Satan, then seek refuge in Allah. Indeed, He is All-Hearing, All-Knowing" (Qur'an 7:200), refers to a person's inclination towards evil, not yawning.