Is the form "لأفعلنّ" (I will surely do) or "لأكتبنّ" (I will surely write) considered an oath or a vow, even if the speaker did not intend it as such, especially if the "ل" (laam) is the lam of emphasis in the answer to an omitted oath? And what is the ruling if someone uttered it in the past, ignorant that it might be considered an oath, and does anything ensue if they broke it? And does the ruling differ if the "ل" (laam) is omitted, so one says "سأفعلنّ" (I will do) without intending an oath or a vow?