Rashid, along with team-mates Liam Plunkett and David Willey, was made available by the England and Wales Cricket Board for Yorkshire’s final two games of the season, and played in last week’s 10-wicket defeat to Somerset.
But the 28-year-old, who has taken 32 County Championship wickets at an average of 33.84, has opted to sit out the crunch clash, which could conclude with Yorkshire being crowned champions for a third successive summer.
“I have not travelled down with the Yorkshire lads this week as one of my closest family members has been very ill and recently admitted to hospital,” said Rashid.
“I didn’t feel that I am in a strong enough mental frame of mind to be at my best. Although I did make myself available if I was required to play I felt I could be letting the lads down.
“But coupled with my personal reasons I have also had a heavy period of cricket recently for Yorkshire and England which has been both physically and mentally draining.”
Head coach Jason Gillespie admitted on Sunday that he was “frustrated” by Rashid’s decision, while Yorkshire skipper Andrew Gale wrote on Twitter: “He wants to rest. That’s his decision. I’ll take 11 lads on the field who will give everything to win.”
Yorkshire can snatch the title if they beat Middlesex and at least match the number of points accrued by Somerset in their clash with already-relegated Nottinghamshire. If table-toppers Middlesex win, they will be champions regardless of the Somerset result.