In homes, on the streets and in places of worship across the UAE, there was quiet at the weekend as people observed the period of mourning.
The death of Sheikh Khalifa has left a gap in the lives of many.
And in the days after his passing, some of the people who knew him best have reflected on the man and how generous he was.
“I will forever miss his calmness,” said Emirati businessman Mohammed Al Fahim. “I've never known him once to lose his temper or get angry with anyone."
Mr Al Fahim grew up in Abu Dhabi with Sheikh Khalifa and experienced the challenging days before the discovery of oil in 1958. His book From Rags to Riches, is a classic account of how the emirate transformed during those years.
Mr Al Fahim paid tribute to Sheikh Khalifa as a man who helped his people throughout his life.
"I will miss his presence," said Mr Al Fahim. "He was a father figure to a lot of people — a father who never tired of listening to our complaints and demands. He was a kind ruler who took action more than he spoke."
Nasser Al Nowais, chairman of the Abu Dhabi-based Rotana Hotels Group, said Sheikh Khalifa was one of a kind.
“No one was like him,” Mr Al Nowais said. “In his humanity, his humility, his kindness and his care for others.”
As Mr Al Nowais’s direct manager at the Abu Dhabi Fund, Sheikh Khalifa was second to none in his kindness and humility, he said.
“He was approachable and cared about all his employees," said Mr Al Nowais. "Every project I presented to him, he supported and encouraged. He cared about the well-being of people not only in the UAE, but all over the world.”
Many people speak of Sheikh Khalifa's commitment to people's happiness and his generosity.
Mohamed Al Ameri, 32, said his father knew Sheikh Khalifa and often told stories about him
“In 2006, Sheikh Khalifa visited the Bedouins [in the desert] and they gave him welcoming gifts of food and fruits,” Mr Al Ameri said.
“I remember Sheikh Khalifa asking the name of each individual who sent a dish," said Mr Al Ameri. "He later thanked them personally for their generosity and made sure they were supported. Losing him is like losing an elder brother or a father."
Ali Al Shorafa, former director of the presidential court of UAE Founding Father, the late Sheikh Zayed bin Sultan Al Nahyan, also remembered Sheikh Khalifa fondly.
Mr Al Shorafa said Sheikh Khalifa gave strength and support to his brother and now President, Sheikh Mohamed.
“The late president Sheikh Khalifa played a vital role in giving Sheikh Mohamed unconditional support. He trusted his abilities to strengthen the UAE’s relationship with the rest of the world,” Mr Al Shorafa said.
“With his support, Sheikh Mohamed has achieved regional and international respect through the UAE's humanitarian stance, with countries going through crises and disasters, as well as through supporting Arab initiatives.” he said.
“History will forever remember Sheikh Khalifa for his unconditional support to Sheikh Mohamed and goals to unite the Arab world and build bridges to preserve national and regional security.”
UAE flags at half staff — in pictures
