To express taking action to prevent an unwanted outcome ("so that not" or "lest"), Farsi uses the negative purpose conjunction مبادا.
Because the prevented action is hypothetical, the verb following مبادا is in the present subjunctive. Since مبادا itself carries a negative meaning (literally "may it not be"), the following verb is always affirmative.
| Be careful because of the snow, lest you crash. | به خاطر برف احتیاط کن مبادا تصادف کنی.be khâtere barf ehtiyât kon mabâdâ tasâdof koni. |
| Take the map with you lest we get lost in the forest. | نقشه را با خودت ببر مبادا در جنگل گم شویم.naqshe râ bâ khodat bebar mabâdâ dar jangal gom shavim. |
Notice in the sentences above that "تصادف کنی" (you crash) and "گم شویم" (we get lost) are affirmative verbs. The negative meaning comes entirely from مبادا.
Precautions and Backup Plans
This structure is common when discussing taking precaution (احتیاط کردن), bringing spare (یدکی) items, or navigating ice (یخ).
| I am taking spare gasoline lest it run out on the road. | من بنزین یدکی میبرم مبادا در جاده تمام شود.man benzin yadaki mibaram mabâdâ dar jâdde tamâm shavad. |
| Fasten the chain to the tire lest we get stuck in the snow. | زنجیر را به لاستیک ببند مبادا در برف گیر کنیم.zanjir râ be lâstik beband mabâdâ dar barf gir konim. |
The main clause describing the precaution can be in any tense—such as an imperative command, present indicative, or past tense—while the verb after مبادا remains in the present subjunctive.
| We did not go towards the mountain lest we get stuck in the ice. | ما به سمت کوه نرفتیم مبادا در یخ گیر کنیم.mâ be samt-e kuh naraftim mabâdâ dar yakh gir konim. |
| Take the spare key lest the first key get lost. | کلید یدکی را بردار مبادا کلید اول گم شود.kalid-e yadaki râ bardâr mabâdâ kalid-e avval gom shavad |