• pratijñām — a promise
  Accusative of pratijñā — formal vow before witnesses. In dharma-śāstra a pratijñā binds the kṣatriya; here it binds Śālva only to his death. Vows untethered from dharma are ropes that hang the swearer.
• ayādavām — devoid of Yādavas
  Negative compound (a + yādava). Since Kṛṣṇa Himself is a Yādava (yadu-pati), to make the earth ayādava is to make it akṛṣṇa — an explicit declaration of war against Bhagavān, however ignorantly framed.
• kṣmām — the earth
  Accusative of kṣmā — Bhū-devī, who in SB 10.1.17 had prayed to Brahmā precisely for relief from such kings. Śālva imagines himself the earth's saviour while being one of the burdens the earth begged to be freed from.
• pauruṣam — prowess
  From puruṣa. Pauruṣa is manly valor; the Bhāgavatam consistently contrasts asuric pauruṣa (self-derived, soon-broken) with the daiva pauruṣa of devotees who fight knowing Bhagavān is the doer (cf. Arjuna at Kurukṣetra).
• paśyata — just see
  Imperative plural of √paś. The asura always demands an audience: see my power. The devotee instead asks the Lord to see him (paśya mām, Gītā 11.7). The grammar of the eye reverses across the asura/devotee line.

• What vow am I quietly carrying that pride won't let me revisit?
• Where could releasing a wounded vow be more freeing than fulfilling it?

Like a man who, stung by a wasp, vows aloud to empty the air of insects — the vow announces only the depth of his sting. Śālva's promise to make the earth ayādava is the cry of a wound, not the speech of a hero.