A real-estate entrepreneur will leave in his will at least $3 million to the Harvard Divinity School.

William Nickerson said yesterday the income from $3 million of his $6 million estate would be used for the Divinity School. The Divinity School would oversee the division of the remaining $3 million between three other American divinity schools, he added.

The gift, which the University will begin to accrue on Nickerson's death, is among the largest personal bequests ever left to the University. It is the largest gift given by an individual to the Divinity School, sources said.

The income earned by the Div School will be used for a scholarship fund and to establish a chair in business ethics, Nickerson said.

Nickerson--the author of the bestselling book. "How I Turned $1000 into $1 Million in Real Estate"--said he and his wife chose Harvard to be the major recipient of the gift after a series of meetings with George Rupp. dean of the School.

"We wanted to find a school that professes a liberal theology, and by that I mean one that respects all religions," Nickerson said. "We thought Harvard would be more fundamental than it was, but we found out the School was ahead of us," Nickerson added.

Congregationalists for 50 years, the Nickersons said they had "heard and respected" many ministers trained at Harvards.

Under the terms of the agreement--described by one University official as "very, very complex,"--half the estate will be turned over to the University on the death of either Mr. or Mrs. Nickerson, and the other half will revert to Harvard when the other dies.

"The trust represents a sophisticated estate plan combining provision for Nickerson's family members with major support for Harvard divnity, school and other charitable institutions." Divinity School development officer Alex Stewart said yesterday, adding that the estate will provide "current support and permanent stability" for the scholarship fund and the business ethics chair.

Nickerson, whose real estate philosophy centered on finding prospects that could be improved and sold at a high return said that half the income from the estate would go to his direct heirs while they remained alive, and on their deaths the principal would revert entirely to the Divinity School.