Rest, who clinched the title for the 26th time in the tournament's 51st year, had been virtually assured of supremacy Saturday itself after notching up 296 for 4 in their second innings for an overall lead of 413 runs at the Wankhede Stadium.
On Sunday, Harbhajan Singh-led Rest side increased the overall lead to a mammoth 506 when they declared their second innings closed at 389 for 5, with Ambati Rayudu remaining unbeaten on 156 after batting for over six hours and hitting 12 fours and 4 sixes.
With draw the only result barring a collapse by Mumbai, the home team cruised along to 160 for 4 wickets with Jaffer, after being ignored for the Test squad against Australia by the selectors who met here, compiling an unbeaten 101 before the game was called off by mutual consent after the third mandatory over in the last hour of play.
Rest, thus, retained the crown they lifted by outclassing Rajasthan by an innings and 79 runs in September last at Bangalore.
Rayudu was on 118 and Suresh Raina on 40 when game commenced this morning and the latter got out after notching up 71 with 5 fours and 3 sixes to follow up his first innings top score of 134 out of 526.
The duo completed the 100 of their fifth wicket partnership off 160 balls, Raina reached his half century in 94 balls and then got out to a leading edge to be caught at short third man off young left arm spinner Vishal Dabholkar.
Raina was out in the 12th over to end his 145-run partnership with Rayudu. Harbhajan then applied closure to the innings with Rayudu, who faced 289 balls, and Wridhiman Saha (20) at the crease, 52 minutes before lunch.
Chasing the improbable target, Mumbai lost the wickets of opener Aditya Tare (11), Ajinkya Rahane (25), Rohit Sharma, who flopped for the second time in the match by scoring one after his duck in the first innings, and captain Abhishek Nayar (2).
Jaffer and Rahane, who made 80 and 83 respectively in the first innings, put on 53 runs in 85 balls for the second wicket before the latter was sent back by Harbhajan.
Tare, dropped by Rayudu at long on off Harbajan, fell to the rival captain two runs later, caught in the leg trap and the off-spinner, selected in the Indian squad for the first two Tests against Australia, sent back Rahane in a similar fashion to show encouraging return to wicket taking ways ahead of the four-match series.
Jaffer batted for 200 minutes and struck ten fours in his 141-ball knock and also crossed the 1,000-run mark to become the highest scorer in the tournament’s history to remain unbeaten along with Ankit Chavan (12) when stumps were drawn for the last time.
Harbhajan picked up 2 for 38 while Pragyan Ojha dismissed Rohit by having the batsman, who again had a rush of blood early in his innings like in the first, through a catch at mid off and finished with 1 for 45. Raina accounted for Nayar.