«لِنَقْبِضَ ... وَلِنَسْتَنْقِضَ»
So that we may receive ... and obtain what is due.
Both present-tense verbs follow a lām of purpose and are in a dependent, subjunctive construction. The first comes from q-b-ḍ, to take or receive into one’s possession. The expanded form of the second emphasizes obtaining the assigned payment.
«لِنَقْبِضَ الصِّلَاتِ»
So that we may collect the benefactions.
The grammatical feature helps identify the speaker’s specific objective rather than treating these forms as independent reports of completed actions.