His statement: “If he swears that he will do it, he is not absolved of his oath unless he does all of it.” If he swears that he will do something, he is not absolved of his oath unless he does it in its entirety. For example, if he says, “By Allah, I shall write the chapter on divorce from Zād al-Mustaqniʿ,” then writes two lines and says, “I am not going to write any more,” we say: he has broken his oath, because he is not absolved of it unless he completes the whole task.
Know that what the author has mentioned here is governed by intention. Thus, if he intended something specific, that intention is given effect, because the first thing to which we refer in matters of oaths is the intention of the one who swore, as will come, if Allah wills.