The head of the Al-Wefaq group had been sentenced in July 2015 to four years in jail after being convicted of inciting so-called hatred in the Al Khalifa-ruled Persian Gulf kingdom.
But the appeals court in May more than doubled his jail term to nine years after reversing an earlier acquittal on charges of calling for regime change by force.
The court of cassation set October 17 as a new date to examine Salman's sentence.
His arrest in December 2014 sparked protests in Bahrain.
Salman's jail sentence is part of a crackdown on the Persian Gulf nation's largest opposition group, which has been dissolved by a court order over false accusations of "harbouring terrorism."
Al-Wefaq had the largest parliamentary bloc before its MPs walked out in February 2011 in protest to a deadly crackdown on Islamic Awakening-inspired protests.
The crackdown on Wefaq has drawn criticism from UN chief Ban Ki-Moon and Bahrain's allies in Washington, as well as rights groups.
Hundreds of pro-democracy people have been arrested and put on trial since security forces backed by Saudi-led troops crushed in March 2011 month-long protests that demanded democratic reforms.
Authorities have also stripped at least 261 people of their citizenship since 2012, according to the Bahrain Centre for Human Rights, including the country's Shiite spiritual leader Sheikh Isa Qassem.
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