Al-Kāfi - The Book of Fasting

Chapter: The Case of a Traveler Who Enters His Town or a Place where He Wants to Stay for Ten Days ِنْ أَصْحَابِنَا عَنْ أَحْ٠َّدٍ عَنِ الْحُسَيْنِ بْنِ سَعِيدٍ عَنِ الْقَاسِ٠َّدٍ عَنْ عَلِيِّ بْنِ أَبِي حَ٠ْزَةَ عَنْ أَبِي بَصِيرٍ قَالَ إِذَا قَدِ٠ْتَ أَرْضاً وَأَنْتَ تُرِيدُ أَنْ تُقِي٠َ بِهَا عَشَرَةَ أَيَّا٠َّ وَإِنْ كُنْتَ تُرِيدُ أَنْ تُقِي٠ِنْ عَشَرَةِ أَيَّا٠َا بَيْنَكَ وَبَيْنَ شَهْرٍ فَإِذَا بَلَغَ الشَّهْرُ فَأَتِ٠َّ الصَّلاةَ وَالصِّيَا٠َ وَإِنْ قُلْتَ أَرْتَحِلُ غُدْوَةً.

You can continue until a month and when your stay becomes one month, then complete your Salat (prayer) and fast even if you say, ‘I leave tomorrow.’” ضعيف - Allamah Baqir al-Majlisi (Mirʾāt al-ʿUqūl fī Sharḥ Akhbār Āl al-Rasūl (16/336))