We have explained in our article Biblical Formatting located on the world wide web at http://www.Rashiyomi.com/biblicalformatting.pdf, that the Biblical Author indicates bold, italics, underline by using repetition. In other words if a modern author wanted to emphasize a word they would either underline, bold or italicize it. However when the Biblical author wishes to emphasize a word He repeats it. The effect - whether thru repetition or using underline - is the same. It is only the means of conveying this emphasis that is different.

Verse Ex23-05c states perhaps you will see the donkey of your enemy overburdened with transport and you will abstain from helping him? You must, with his help, unload unload. Rashi commenting on the repeated words unload unload connoting an unspecified emphasis states You must always unload the donkey even e.g. if the person is elderly and cannot help you.

Advanced Rashi: To fully appreciate this Rashi we bring in other aspects of the verse which come from the use of the Grammar, Rule #3 and the Contradiction, Rule #5. We have fully dealt with these aspects of Rashi elsewhere but bring them lightly here to more fully appreciate the current Rashi.
• From the use of a full word to indicate with him we infer that you shoud only help when the owner of the donkey participates with the unloading (Use of a full-word pronoun indicates a restrictive emphasis - only help him when he is with you, not if he is sitting on the side.; the traditional indication of a pronoun is through a suffix letter.)
• but from the repeated unload unload we infer that you must always unload even if the owner is not there.
Thus these two emphasii - only with him vs. always unload - create two contradictory albeit unspecified emphasis. Such appearances of dual emphasis occurs frequently in the exegetical literature. Rashi following the mechiltah and talmud resolves this by skillfully identifying two cases
• Obviously if the person is elderly you must still unload even though he can't help
• But equally obviously if the person is a smart-alec who sits down and says 'You are obligated to unload - go do it' then you do not have to assist.

The above Rashi is therefore fundamental and illustrative of a broad class of Rashi comments with talmudic flavor. The serious student of exegesis would do well to study it throughly.