Well-wishers wear pink shirts as they pray in front of a picture of Thailand's King Bhumibol Adulyadej at Siriraj Hospital in Bangkok, Thailand, October 11, 2016. REUTERS, Chaiwat Subprasom

Thais on Tuesday wore pink for 88-year-old King Bhumibol Adulyadej, a color they believe will help improve the monarch’s health, two days after the palace said he was in an unstable condition.

King Bhumibol, the world’s longest reigning monarch, is widely revered in Thailand. During his seven decades on the throne the king, who is also seen as a unifying force for the country, has intervened when events threatened to plunge Thailand into crisis.

The palace said on Sunday the king’s health was “not stable” following hemodialysis treatment in hospital, a process to purify the blood. It said a ventilator was deployed after the monarch’s blood pressure dropped.

It is unusual for the palace to state that the king’s health is not stable. Statements on the king’s are usually issued after the monarch’s condition shows improvement.

Many Thais are highly superstitious and some believe brightly colored clothes can attract good luck.

Messages shared on social media since the palace statement have urged Thais to wear pink, a color which first became important a few years ago when royal astrologers said it was good for the king and would promote well-being. Since then, the king has sometimes been seen in public wearing pink.

Well-wishers on Tuesday flocked to Siriraj Hospital in Bangkok where the king has spent much of the past year.

News about the king’s health is closely monitored and the wording of palace statements on the king’s health is intensely scrutinized.

Strict laws protecting the royal family suppresses any public discussion of the king’s health.