SQL> connect sys as sysdba
Enter password:
Connected.

SQL> grant create user ,drop user , lock any table to sam;

SQL> conn sam
Enter password:
Connected.

SQL> create user san identified by san;
User created

Initially user sam having  CREATE USER privilege. 

User sam trying to grant  following privilege.

SQL> grant connect ,resource to san identified by san;

grant connect ,resource to san identified by san
* ERROR at line 1:
ORA-01031: insufficient privileges

SQL> grant create session to san;
grant create session to san
* ERROR at line 1:

ORA-01031: insufficient privileges

conn  /as  sysdba
SQL> grant dba to sam;
Grant succeeded.

SQL> conn sam
Enter password:
Connected.

SQL> grant connect ,resource to san identified by san;
Grant succeeded.

SQL> grant connect , resource to rose identified by rose;
Grant succeeded.

SQL>  grant connect , resource  to preeti identified by preeti;
Grant succeeded.

SQL> grant connect ,resource to san identified by san;
Grant succeeded.

SQL>grant connect ,resource to x identified by x;
User created.

SQL> grant create user to x with admin option;
Grant succeeded.

SQL> conn x
Enter password:
Connected.

SQL> create user y identified by y;
User created.

SQL> grant connect ,resource to y;
grant connect ,resource to y
* ERROR at line 1:
ORA-01031: insufficient privileges

SQL> conn sam
Enter password:
Connected.

SQL> create user test identified by test;
User created.

SQL> grant connect,resource to test;
Grant succeeded.

SQL> grant connect , resource to chris identified by chris;
Grant succeeded.