Sunan an-Nasa'i, Volume 3, Book 22, Hadith 2276 (DarusSalam) ⓘ
It was narrated from Anas that the Prophet said: "Allah has waived meaning half of the prayer and fasting for the traveler, and from pregnant women and the sick. "(Hanas)
أَخْبَرَنَا عُمَرُ بْنُ مُحَمَّدِ بْنِ الْحَسَنِ بْنِ التَّلِّ، قَالَ حَدَّثَنَا أَبِي قَالَ، حَدَّثَنَا سُفْيَانُ الثَّوْرِيُّ، عَنْ أَيُّوبَ، عَنْ أَبِي قِلاَبَةَ، عَنْ أَنَسٍ، عَنِ النَّبِيِّ صلى الله عليه وسلم قَالَ " إِنَّ اللَّهَ وَضَعَ عَنِ الْمُسَافِرِ نِصْفَ الصَّلاَةِ وَالصَّوْمَ وَعَنِ الْحُبْلَى وَالْمُرْضِعِ " .
also referenced under: Hadith 2274 (Reference) & Book 22, Hadith 185 (In-Book)