The first two Ahadith forbid us from drinking water out of the mouth of a water-skin, whereas, once Messenger of Allah (PBUH) himself had done so. This shows that not to drink water by this way is also approved. However, if needed, it is allowable. For this reason Imam An-Nawawi clarified that to drink water out of the mouth of the water-skin is conditionally permissible and not forbidden. But to eschew it is desirable. Likewise, to receive benediction from the Prophet's left-overs is permissible as long as this does not take the form of worship and glorification.