How To Run Xp_send Mail From A Store Procedure

hi and thanks for your help, I created the following store procedure to run and send query result via sql mail. how can I run the xp_sendmail.... from a store procedure if I cannot use user Master in a store procedure or trigger. ?

Thanks
Ali
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create procedure p_ci_notification as

if exists(
select customer_invoice_id,invoice_total,convert(varchar( 10),date_of_service,101) as date_of_service
from ci_master
where convert(varchar(10),date_of_service+60,101) > convert(varchar(10),getdate(),101)
and invoice_total >5000
and customer_invoice_id not in (select customer_invoice_id from ci_notification )
)

BEGIN
insert ci_notification(customer_invoice_id,invoice_total, date_of_service)
select customer_invoice_id,invoice_total ,date_of_service
from ci_master
where convert(varchar(10),date_of_service+60,101) > convert(varchar(10),getdate(),101)
and invoice_total >5000
and customer_invoice_id not in (select customer_invoice_id from ci_notification )

-- send the email
use master
EXECUTE xp_sendmail @recipients = xzy@aol.com;abc@yahoo.com'
,@message = 'Erick,
how to send a query result via sql mail'
,@query ='select customer_invoice_id,invoice_total,convert varchar (10),date_of_service,101)as date_of_service
from cesweb.cesi_intranet.dbo.ci_notification
WHERE notified =0'

-- update the flag
--select customer_invoice_id,invoice_total,convert(varchar( 10),date_of_service,101) as date_of_service,notified
--from ci_notification
-- truncate table ci_notification
update server.dbname.dbo.ci_notification set notified = 1 WHERE notified =0
END

------------------------------------------------------------------------
ERROR message that I got:---------------------
Server: Msg 154, Level 15, State 1, Procedure p_ci_notification, Line 20
a USE database statement is not allowed in a procedure or trigger.