When. On going out — the longer of the two supplications for the door. It suits a day whose difficulty will be other people: a dispute to settle, a meeting that may turn, a journey among strangers.
The words. Four pairs, and each pair is the same verb twice, first active and then passive: adilla / udall, to stray or be led astray; azilla / uzall, to slip or be made to slip; azlima / uzlam, to wrong or be wronged; ajhala / yujhala 'alayy, to behave ignorantly or have someone behave so towards me. Arabic can do this in one breath because the passive is a vowel change inside the same word, and the effect is a mirror: every harm is named twice, once as something you might do and once as something that might be done to you.
Straying and slipping are not the same. Dalal is losing the road — a matter of direction, of ending up somewhere you did not intend. Zalal is the foot going out from under you on a road you can still see. One is a wrong path, the other a fall on the right one, and the supplication refuses to collapse them.
The last pair is about temper. Jahl in older Arabic is not lack of information. It is the hot-headed, overbearing conduct that the pre-Islamic age was named for. So the fourth request is not to be spared stupidity but to be spared a scene — mine or someone else's.
Why the active comes first. In all four pairs the speaker names himself as the possible wrongdoer before naming himself as the victim. A person who says this every morning has been made, four times, to consider that the danger outside the door might be him.