وَمَنْ دَخَلَ بَلَدًا وَلَمْ يَنْوِ أَنْ يُقِيمَ فِيهِ خَمْسَةَ عَشَرَ يَوْمًا، وَإِنَّمَا يَقُولُ: غَدًا أَخْرُجُ، أَوْ بَعْدَ غَدٍ أَخْرُجُ، حَتَّى بَقِيَ عَلَى ذَلِكَ سِنِينَ: صَلَّى رَكْعَتَيْنِ.
Translation: Someone enters a town without intending a fifteen-day stay, repeatedly expecting to leave tomorrow or the next day, and remains that way for years, still prays two rak‘ahs.
This describes an indeterminate stay: no fixed fifteen-day intention is ever made, regardless of how much time has passed.