The Avenfield case was one of three references filed by NAB on orders of the Supreme Court of Pakistan in the landmark Panama Case verdict on July 28, 2017.
Now both Sharif and his daughter are in London tending to Kulsoom, who is critically ill.
Talking to reporters in London later in the evening Nawaz said he would return to Pakistan, but avoided giving a specific date.
As per an election campaign travel log of party supremo Imran Khan, he will be making several campaign stops at 25 different cities of Punjab, Khyber-Pakhtunkhwa and Sindh ahead of the July 25 general election. Kamran Yousaf has this report.
What is Avenfield reference case?
"(Sharif) has been awarded 10 years imprisonment and an eight million pound ($10 million) fine" over the purchase of high-end properties in London, defense lawyer Mohammad Aurangzeb told AFP.
2007 - Returns from exile to contest elections the next year as part of a political deal that ended Musharraf's military rule.
Sharif, who at times during his premiership appeared to seek a better relationship with Pakistan's arch-enemy India, has since repeatedly accused the military of wanton political interference.
Nawaz Sharif and his daughter Maryam Nawaz wave at supporters in Islamabad.
NAB deputy prosecutor general Sardar Muzaffar Abbasi said the accused have 10 days to file an appeal against the verdict. "Maryam was given seven years of rigorous imprisonment and imposed two million pounds (over United States dollars 2.6 million) and her husband Muhammad Safdar was awarded one year rigorous imprisonment", the NAB prosecution team chief Sardar Muzaffar Abbasi told media outside the court. But Nawaz will have to first face formal arrest because an absconder, according to the law, has no right of audience before a court.
The Supreme Court agreed to investigate the Sharif family's finances after Khan threatened street demonstrations to protest graft.
Three of Sharif's four children - Maryam, his presumptive political heir, and his sons Hasan and Hussein - were implicated in the papers.
During the trial, the NAB presented around 21 witnessed to prove that Sharif family can not justify the money trail to buy four apartments in Avenfield House, Park Lane, London.
Last month Pakistan was put on the intergovernmental Financial Action Task Force's "Grey List" for failing to curb anti-terror financing and there are many in the country who fear a government led by Imran Khan will champion conservative Islamic ideals and encourage more radicalization in the country and that this will only lead to more instability, in Pakistan and across South Asia.
Analysts believe that if they return, it might boost the chances of good showing in elections by the PML-N due to sympathy vote.
Sharif's younger brother, Shehbaz Sharif, who has taken over the PML-N leadership, said on Thursday recent action by the anti-graft National Accountability Bureau and the judiciary had cast doubt over the election.