USE abc

Create ROLE db_exec
go

GRANT EXECUTE TO db_exec
go

EXEC sp_addrolemember 'db_exec', 'abc_user'
go

use master
go

grant exec on sp_OACreate to abc_user
GO

SELECT * FROM master.sys.database_permissions AS dp
JOIN sys.system_objects AS so
ON dp.major_id = so.object_id
WHERE permission_name = 'EXECUTE' AND name = 'sp_OACreate'