ENOfficial
Ibn Abbas (Allah be pleased with them) reported: A woman lifted up her child and said: Messenger of Allah, would the child be credited with having performed the Hajj? Thereupon he said: Yes, and there would be a reward for you.
Source: sunnah.com
Other translations
Arabic
حَدَّثَنَا أَبُو كُرَيْبٍ، مُحَمَّدُ بْنُ الْعَلاَءِ حَدَّثَنَا أَبُو أُسَامَةَ، عَنْ سُفْيَانَ، عَنْ مُحَمَّدِ بْنِ، عُقْبَةَ عَنْ كُرَيْبٍ، عَنِ ابْنِ عَبَّاسٍ، قَالَ رَفَعَتِ امْرَأَةٌ صَبِيًّا لَهَا فَقَالَتْ يَا رَسُولَ اللَّهِ أَلِهَذَا حَجٌّ قَالَ " نَعَمْ وَلَكِ أَجْرٌ " .
sunnah.com