An exclusive Post photo reveals for the first time an elderly Brooklyn couplein a quiet moment together — before they were allegedly stabbed to death by their disturbed son inside their home.

Jacob and Rachel Sperber, both 75, look very much the lovable older pair in the snapshot, which shows them huddling next to each other on a city subway train.

The husband and wife were fatally stabbed in their Borough Park home around 5:20 p.m. Saturday — allegedly at the hands of the troubled 46-year-old son they cared for.

The son, who has not been publicly identified, is in police custody as a person of interest but has yet to be charged, law-enforcement sources have said.

He has been described by locals as a “weird,” “awkward” and having “issues,” while his parents were said to have been “very nice” and “quiet” and beloved in the community.

“They were good, they raised him,” the couple’s neighbor told The Post on Sunday.

“They provided. He was mentally ill,” the man said. “They did everything they could for him, and this is how he repaid them. It is disgusting. It is a terrible thing.”

The suspected killer barricaded himself inside the family apartment at 1158 45th St. after the stabbings before he was taken into custody and hauled away on a stretcher, police said.

Neighbors described the suspect as “sometimes depressed, sometimes high.”

His father, meanwhile, was “a special person” who would invite hungry locals into the family home and provide them with food and comfort.

“He was from a different generation,” local resident Shlomo Antin told The Post on Saturday of the dad. “There were so many people who knew him.”

On Sunday, a group of Hassidic men stood guard over the scene of the slaughter, intercepting reporters and urging for privacy for the family and the community.