Ta'anis 10b - Vowing on Condition

The gemara says that if one makes a neder on condition that someone gets better, even if they get better, or die (rashi), before the vow is carried out, they are still required to carry out their vow. Rashi (d.h. al hatzara) seems to explain that it is improper to make conditions with Hashem (bec. it is considered chutzpah), therefore he must complete the vow. It would seem clear that to make an explicit condition would certainly be an issur. Rashi implies that whether the condition is explicit or not, one is compelled to complete their vow to avoid it looking as if they are making conditions with G-d, but the vow is not really binding since it was pending on the condition.
However, the Rema in Y.D. (220:15) qualifies the gemara that the vow must only be completed when the stipulation is not spoken out, but if he explicitly states he is giving the tzedaka or fasting on the condition that the person is healed, he does not have to complete the vow if the person dies. Clearly he understand that if one did not explicitly make a condition, they are bound by their words to complete their vow even if their intent was to vow only for this purpose (not like Rashi).
To fit the Rema with rashi it seems that the rema agrees that it is forbidden to vow with a condition bec. it is considered to be a display of chutzpa (as the rema indicates at the end of the paragraph, that it is a violation of serving Hashem without expecting reward). Therefore, if the condition is not explicit we assume that he did not mean to make the vow pending on the condition since this would be an issur, so we require the vow to be carried out regardless of the outcome. But, if the stipulation was explicit, although he violated a semi-issur by doing so, the stipulation is binding and if the person dies he does not have to complete the vow.

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