Mokṣayiṣyāmi ('I shall liberate') appears as the divine guarantee at the heart of the Charama Śloka — sarva-dharmān parityajya māmēkaṃ śaraṇaṃ vraja / ahaṃ tvā sarva-pāpebhyo mokṣayiṣyāmi mā śucaḥ (BG 18.66). After instructing Arjuna in the entirety of the Gītā, Bhagavān Kṛṣṇa distils His supreme teaching into this one verse: abandon all self-dependent means, take refuge in Me alone, and I personally (aham) guarantee your liberation (mokṣayiṣyāmi) from all sins (sarva-pāpebhyaḥ). The word mā śucaḥ ('grieve not') then removes even the residual anxiety of the surrendered soul.
In Śrī Vaiṣṇava exegesis, mokṣayiṣyāmi is the most precious word in all of scripture. Ācāryas note several features: (1) The future tense (-iṣyāmi) is an unbreakable promise (pratijñā), not a conditional statement. (2) The first person singular aham ('I') emphasizes that Bhagavān Himself acts as the liberating agent — no intermediary, no further effort required from the prapanna. (3) Sarva-pāpebhyaḥ ('from all sins') removes any fear that the weight of accumulated karma could obstruct liberation. Maṇavāḷa Māmunigaḷ, in Upadesarattinamalai, declares that the prapanna who truly hears mokṣayiṣyāmi need never tremble again.
The word is inseparable from mā śucaḥ ('do not grieve'): together they constitute the complete reassurance that Bhagavān offers. Piḷḷai Lokācārya explains in Śrī Vachana Bhūṣaṇam that the prapanna's one remaining duty is to trust this word implicitly — a trust that is itself the fruit of Bhagavān's grace. Any residual anxiety about one's own unworthiness is answered by mokṣayiṣyāmi: it is His act, not ours.