Prime Minister Dr Mahathir Mohamad's wife Dr Siti Hasmah Mohd Ali became emotional when she shared the memories of her brother at a book launch today.

She also revealed an incident when Ismail Mohamed Ali once asked her: "Hasmah, where did Mahathir get the money to build that house?"

Siti Hasmah said Ismail, the first Malaysian to be appointed as Bank Negara governor, was a very strict person and yet a true gentleman.

“My brother is very straight in the financial aspect. There was one time... my husband became a minister then, and suddenly I was called (by my brother).

“He said 'Hasmah come to my office'. He did not tell me why, but he said he wanted to ask me something and asked me to be in his office. So I went to Bank Negara for the first time, wondering what was his intention.

“Even before I sat down, he said, ‘Hasmah, where did Mahathir get the money to build that house?'" she said in her speech at the launch of her book Tun Ismail Mohamed Ali: Paragon of Trust and Integrity at Sasana Kijang in Kuala Lumpur.

Siti Hasmah recalled that she was very sad when her brother questioned her but she kept calm and explained the situation.

“I said, 'Abang Ngah, we sold the house, our own, the first house in Alor Setar. And being a government servant, Mahathir got a loan from the government'."

After the explanation, she said she was equally shocked by his expression.

“He said ‘Hmm’, that was what he said, ‘Hmm’.”

Ismail retired as Bank Negara governor in 1980, and the following year Mahathir was sworn in as the fourth prime minister.

Siti Hasmah also spoke about the time when her brother's body got weaker and weaker, and she wrote a note saying "Do not give my brother cigars" and pasted it at the ward he was hospitalised.

She could not hold back her tears when she spoke about the moments before Ismail passed away.

“The doctor checked his blood pressure and the family was informed... (her daughter) Marina then informed me.

“I cried. That was the day my husband came to see me at the hospital, fully dressed because it was the Prophet Muhammad’s birthday. My brother was born on Hari Raya Haji and he passed away on Prophet's special birthday," she said.

Ismail was born in 1918, the second of 10 siblings. He studied at Victoria Institution in Kuala Lumpur and did his tertiary education at the Cambridge University in England.