In cricket, an over has six consecutive balls that are bowled by a single bowler from one end of the pitch to the batsman at the other end. After six deliveries, the umpire calls 'over' and a new bowler comes to bowl. Legal deliveries are those balls which are bowled by a bowler that are neither wide nor no balls.
In the Test Cricket history, Sri lankan magical spinner Muttiah Muralitharan holds the record of bowling the most legal delivers. He bowled 44,039 legal deliveries in Test cricket. He retired from Test cricket in 2010 after registering his 800th and final wicket on 22 July 2010 from his final ball in his last Test match.
He also holds the world record for the most wickets in both test and one-day cricket. During his glorious career he took 800 wickets in Tests and 534 wickets in ODI. Next to him, India's Anil Kumble holds the record of delivering maximum legal deliveries in Test cricket.