"Would you say it's difficult for you to be in court giving evidence in a case against your father?" the barrister acting for former NSW Labor MP Eddie Obeid asked his eldest son.

"Unquestionably," Damian Obeid replied from the witness box in the Darlinghurst Supreme Court.

On the third day of Mr Obeid senior's criminal trial, Damian Obeid agreed the family patriarch was a "devoted family man" but denied he took an active role in family businesses at the centre of the case.

He said his father was "very busy" with parliamentary duties and was "fairly late coming home".

The former upper house MP, 72, is accused of misconduct in public office for failing to disclose his family's interest in two cafe leases at Circular Quay when lobbying a senior bureaucrat in 2007 about the plight of waterfront leaseholders.

He has pleaded not guilty to the charge.

The court has heard family matriarch Judith was given $1000 a week in cash takings from the cafes as housekeeping money.

But a key point of contention in the trial is whether Mr Obeid snr himself received cash directly from the businesses.

The Crown says there is an "irresistible inference" he received separate envelopes of cash marked "Dad" or "EO", based on the records of the cafes' bookkeeper, Paul Maroon.

But Damian Obeid, who collected the envelopes of cash each week for his mother, told the court on Wednesday he "never" gave cash to his father.

He said the records were "obviously something [Paul has] come up with" and did not reflect his own instructions.

"Paul's memory is not very good, as you know," he told Crown prosecutor Peter Neil, SC.

Damian Obeid said his father "handed over" the running of the family businesses to his five sons after he entered state Parliament in 1991.

Mr Neil put it to Damian Obeid that he kept his father "updated all the way through" about the concerns of Circular Quay tenants, who were seeking a renewal of their leases without competing in a public tender.

Mr Obeid jnr, his wife and their two children had at that stage moved in with his parents to the family home, Passy in Hunters Hill, to "take care of them in their old age".

"I can't recall any direct discussions with Dad," Mr Obeid jnr said.

Passy, purchased in 2000 for $2.9 million and held in Mrs Obeid's name, was used as security to borrow the money to buy the cafe leases two years later.

The Crown alleges Mr Obeid snr "effectively held out" to a senior maritime bureaucrat, Steve Dunn, that he was making representations on behalf of "arm's length constituents" when he asked Mr Dunn to meet a commercial mediator acting for a group of disgruntled Circular Quay tenants including an Obeid-linked company.

But the defence, led by Brad Hughes, SC, says Mr Obeid did "no more" than ask Mr Dunn to meet the mediator and did not advocate any particular course of action.

The trial continues.