The late Mr Lee Kuan Yew spoke Bahasa Indonesia to only two people - Indonesia's second President Mr Suharto and Defence Minister Ryamizard Ryacudu, the latter told reporters on Friday.
Mr Ryamizard, who was then Indonesia's army chief, recalled asking if he could speak Bahasa Indonesia to the founding father of Singapore.
"My English isn't good, not fluent. May I speak Bahasa with you? Lee Kuan Yew said 'Go ahead. I have no problem with that'," Mr Ryamizard told reporters after signing the condolence book at the Singapore embassy.
Mr Lee then told him: "Just so you know Pak Ryamizard. I speak Bahasa only with two people - Pak Harto (Suharto) and now you."
Recalling their five meetings, Mr Ryamizard said "they clicked" and he would address Mr Lee as "Pak Le", a Javanese term for father.
The defence minister described Mr Lee as a humble leader who reminded him of Indonesian President Joko Widodo.
"He was humble. He was like Jokowi. He talked humbly, down to earth. He always thought about his people. If Lee Kuan Yew didn't exist, Singapore will not exist. Even China managed to advance itself because they learn from Singapore."
Also at the Singapore embassy on Thursday was Mr Hayono Isman, youth and sports minister during the Suharto administration.
Mr Hayono recalled the time in May 1973 when Mr Lee scattered flowers on the graves of two Indonesian marines involved in the 1965 bombing of MacDonald House on Orchard Road in Singapore. Osman Haji Mohamed Ali and Harun Said were executed in Singapore in 1968 for the bombing that killed three people and injured 33 others.
"He was a leader who respected his own country's laws, as well as respected Indonesia, a neighbour who mourned the two soldiers who had been sentenced to death in Singapore," Mr Hayono said.
"That is extraordinary character. Today we feel the benefit of what he did. Not only do Singapore and Indonesia have good relations all these years, but also other countries within Asean."