Aggiorna SQL con due tabelle in Oracle

Question

Ho un SQL come questo

UPDATE A
SET A.TEMSILCI_KOD = 4
FROM S_MUSTERI A, S_TEKLIF B
WHERE A.TEMSILCI_KOD = 9
AND B.BAYI_KOD = 17
AND A.HESAP_NO = B.HESAP_NO

Ma ricevo un errore come questo

Error starting at line 8 in command:
UPDATE A
SET A.TEMSILCI_KOD = 4
FROM S_MUSTERI A, S_TEKLIF B
WHERE A.TEMSILCI_KOD = 9
AND B.BAYI_KOD = 17
AND A.HESAP_NO = B.HESAP_NO
Error at Command Line:9 Column:22
Error report:
SQL Error: ORA-00933: SQL command not properly ended
00933. 00000 -  "SQL command not properly ended"
*Cause:    
*Action:

Dov'è il ERROR?