I’m sure there are other ways to do this but this is pretty easy:

DECLARE
 @SPID INT,
 @Handle binary(20),
 @retVal varchar(8000)
SET
 @SPID = 148
SELECT
 @Handle=sql_handle
FROM
 master..sysprocesses
WHERE spid = @SPID
SELECT
 SqlCommand=convert(varchar(8000), [text])
FROM
 ::fn_get_sql(@Handle)

References