Netanyahu’s office said he had spent the previous day at the Sea of Galilee, a popular vacation spot in northern Israel where temperatures climbed to about 40 degrees Celsius (104 degrees Fahrenheit) amid a stifling country-wide heat wave. After a series of tests, the initial assessment was that the veteran Israeli leader was dehydrated.

After being hospitalized, Netanyahu released a video on social media last night. Smiling, he said that he had been out in the sun on Friday without wearing a hat and without water. “Not a good idea,” he said.

Doctors ordered him to remain in the hospital overnight for further observation, and his weekly Cabinet meeting was delayed by a day and rescheduled for Monday, his office said.

Netanyahu is Israel’s longest-serving leader. He has served multiple terms stretching over 15 years in office. His current far-right government, a collection of religious and ultranationalist parties, took office last December.

Netanyahu is said to be in generally good health, though he was briefly hospitalized last October after feeling unwell during prayers on Yom Kippur, a day when observant Jews fast.