Gallery owner Tim Olsen and his jewellery designer sister Louise Olsen have taken the prominent art auction house to the NSW Supreme Court over the painting called The Mother.

On the rear of the canvas is an inscription that reads: "For my darling Valerie, John Olsen '64".

The plaintiffs say the artist gave the painting to his then-wife Valerie Olsen as a gift following the birth of Louise. Valerie died in 2011.

Tim Olsen says that, in July, a business acquaintance told him Sotheby's was auctioning the painting on behalf of a client.

As executors of their late mother Valerie's estate, Tim and Louise Olsen have asked the court to force Sotheby's to disclose the identity of the vendor and the provenance of the painting.

Late last week, the pair sought an urgent injunction to stop Sotheby's from selling or in any way transferring the painting until the case can be heard.

Mr Olsen told the court that, at some time, his mother said to him: "There was a painting that John did for me when Louise was born that disappeared and it has constantly worried me throughout my life."

The court was also given a letter written by John Olsen on August 4 that says: "I have no memory of selling this painting as it was a gift to my wife Valerie, and I therefore require a provenance."

Painting conservator David Stein told the court the painting had, until recently, been stored in a rolled-up manner. It had been restretched using a new wooden stretcher.

Justice James Stevenson refused the Olsens' application for an interlocutory injunction, saying that almost 50 years had elapsed since the painting "disappeared", yet it was only reported stolen this year.

"There is no evidence before me as to when or in what circumstance in which it disappeared, or what steps were taken to recover it since then." Justice Stevenson said.

The matter will return to court on Wednesday to allow the plaintiffs to present further evidence from John Olsen, who lives in the southern highlands with his fourth wife, Katherine.

Olsen, the 2005 Archibald Prize winner, is still painting in his 80s, and is revered as one of the country's greatest living artists.

His primary subject is landscape and his work is exhibited in all Australian state gallery collections, the National Gallery of Australia in Canberra, and regional galleries across Australia.

Tim Olsen runs the Olsen Irwin art gallery in Woollahra while his sister founded jewellery and homewares brand Dinosaur Designs.