Do not add hint in disorder

SQL> select ID from (select/* + index (SI sie_invoices_n3) */Si. ID from binbin1 Si,
2 binbin2 BS where Si. ID = BS. ID and Si. type = 'ar _ invoice' and
3 Si. import_failed_reason is null and (Si. imp_1__mis_flag is null or Si. imp_1__mis_flag = 'n') and (Si. type! = 'Ap _ invoice'
4 or Si. batch_number is not null) and BS. current_status = '2017 _ has_approved ') Where rownum <6;

No rows selected

Elapsed: 00:00:01. 76

Execution Plan

----------------------------------------------------------Plan hash value: 1985019629-----------------------------------------------------------------------------------------------------| Id  | Operation                      | Name               | Rows  | Bytes | Cost (%CPU)| Time     |-----------------------------------------------------------------------------------------------------|   0 | SELECT STATEMENT               |                    |     5 |   235 |   276K  (1)| 00:55:23 ||*  1 |  COUNT STOPKEY                 |                    |       |       |            |          ||*  2 |   TABLE ACCESS BY INDEX ROWID  | SIE_INVOICES       |     1 |    24 |     3   (0)| 00:00:01 ||   3 |    NESTED LOOPS                |                    |     5 |   235 |   276K  (1)| 00:55:23 ||   4 |     TABLE ACCESS BY INDEX ROWID| WFR_BILL_STATUS    | 99261 |  2229K|  8743   (1)| 00:01:45 ||*  5 |      INDEX RANGE SCAN          | WFR_BILL_STATUS_N4 | 99261 |       |   679   (1)| 00:00:09 ||*  6 |     INDEX RANGE SCAN           | SIE_INVOICES_N3    |     1 |       |     2   (0)| 00:00:01 |-----------------------------------------------------------------------------------------------------Predicate Information (identified by operation id):---------------------------------------------------   1 - filter(ROWNUM<6)   2 - filter("SI"."type"='AR_INVOICE' AND              ("SI"."type"<>'AP_INVOICE' OR "SI"."BATCH_NUMBER" IS NOT NULL) AND              ("SI"."IMP_INTO_MIS_FLAG"='N' OR "SI"."IMP_INTO_MIS_FLAG" IS NULL) AND              "SI"."IMPORT_FAILED_REASON" IS NULL)   5 - access("BS"."CURRENT_STATUS"='300_HAS_APPROVED')   6 - access("SI"."id"="BS"."id")Statistics----------------------------------------------------------          1  recursive calls          0  db block gets     234682  consistent gets          0  physical reads          0  redo size        330  bytes sent via SQL*Net to client        481  bytes received via SQL*Net from client          1  SQL*Net roundtrips to/from client          0  sorts (memory)          0  sorts (disk)          0  rows processed

Capture an SQL statement from AWR and find that there is a hint. After removing the hint, it is fast.
SQL>
SQL> select ID from (select Si. ID from binbin1 Si,
2 binbin2 BS where Si. ID = BS. ID and Si. type = 'ar _ invoice' and
3 Si. import_failed_reason is null and (Si. imp_1__mis_flag is null or Si. imp_1__mis_flag = 'n') and (Si. type! = 'Gl _ voucher'
4 or Si. batch_number is not null) and BS. current_status = '2017 _ has_approved ') Where rownum <6;

No rows selected

Elapsed: 00:00:00. 06

Execution Plan----------------------------------------------------------Plan hash value: 144640525-----------------------------------------------------------------------------------------------------| Id  | Operation                      | Name               | Rows  | Bytes | Cost (%CPU)| Time     |-----------------------------------------------------------------------------------------------------|   0 | SELECT STATEMENT               |                    |     5 |   235 |    23   (0)| 00:00:01 ||*  1 |  COUNT STOPKEY                 |                    |       |       |            |          ||*  2 |   TABLE ACCESS BY INDEX ROWID  | WFR_BILL_STATUS    |     1 |    23 |     3   (0)| 00:00:01 ||   3 |    NESTED LOOPS                |                    |     5 |   235 |    23   (0)| 00:00:01 ||*  4 |     TABLE ACCESS BY INDEX ROWID| SIE_INVOICES       |    26 |   624 |     5   (0)| 00:00:01 ||*  5 |      INDEX RANGE SCAN          | SIE_INVOICES_N8    |   107 |       |     3   (0)| 00:00:01 ||*  6 |     INDEX RANGE SCAN           | WFR_BILL_STATUS_N2 |     1 |       |     2   (0)| 00:00:01 |-----------------------------------------------------------------------------------------------------Predicate Information (identified by operation id):---------------------------------------------------   1 - filter(ROWNUM<6)   2 - filter("BS"."CURRENT_STATUS"='300_HAS_APPROVED')   4 - filter(("SI"."IMP_INTO_MIS_FLAG"='N' OR "SI"."IMP_INTO_MIS_FLAG" IS NULL) AND              ("SI"."type"<>'GL_VOUCHER' OR "SI"."BATCH_NUMBER" IS NOT NULL) AND              "SI"."IMPORT_FAILED_REASON" IS NULL)   5 - access("SI"."type"='AR_INVOICE')   6 - access("SI"."id"="BS"."id")Statistics----------------------------------------------------------          1  recursive calls          0  db block gets         33  consistent gets          8  physical reads          0  redo size        330  bytes sent via SQL*Net to client        481  bytes received via SQL*Net from client          1  SQL*Net roundtrips to/from client          0  sorts (memory)          0  sorts (disk)          0  rows processed