Since 2015, Kagiso Rabada of South Africa has held the record for greatest numbers in an ODI debut.

Charlie Cassell, a fast bowler from Scotland, achieved the record for greatest figures on an ODI debut against Oman in the ICC Men’s Cricket World Cup League 2 match in Dundee, taking 7/21 in 5.4 overs.
Kagiso Rabada of South Africa held the record after taking 6 for 16 against Bangladesh in July 2015 on his ODI debut.
Fast bowler Chris Sole was replaced in the Scotland team for the July 15 game against Oman by Cassell, who was unable to travel due to personal matters.
Cassell was given his cap by Scotland captain Richie Berrington prior to the match against Oman. “You’ve come back from a huge setback, with that massive injury you had, put you out for a year and a bit,” Berrington said. “Just to see your resilience coming back, getting back on the park, and just love watching what you do at Forfs [Forfashire], and just the way how you hold yourself is incredible.”
Beginning his international debut with two deliveries in his opening bowling match against Oman, Cassell bowled Ayaan Khan and trapped Zeeshan Maqsood leg before wicket. Cassell had incredible stats of 1.3-1-0-4 after missing a hat-trick and getting Khalid Kail caught off his fourth delivery. He also had Shoaib Khan caught in his second over.
The sixth wicket for Cassell was Mehran Khan. After that, he got rid of Pratik Athavale to become the only bowler, along with Rabada and Fidel Edwards of the West Indies, to have six wickets in their ODI debut. He then ended Oman’s innings by having Bilal Khan caught behind, earning a record seventh in his debut international.
Scotland brought down Oman’s goal of 91 runs in 21.4 overs, with eight wickets remained and 196 balls bowled, thanks to Cassell’s 7 for 21.