بُلُوغُ الْمَرَامِ
Bulugh al-Maram 437
The Book of Prayer
وَلَهُ عَنْ جَابِرٍ: { أَقَامَ بِتَبُوكَ عِشْرِينَ يَوْمًا يَقْصُرُ اَلصَّلَاةَ } وَرُوَاتُهُ ثِقَاتٌ, إِلَّا أَنَّهُ اُخْتُلِفَ فِي وَصْلِه ِ [1] .
His narration from Jabir (RA) has: Allah's Messenger (RA) stayed at Tabuk for twenty days, and he shortened the prayers (during his stay). [Its narrators are reliable, except that there is difference about whether or not it is Mawsul (unbroken chain of narrators)].
Sunnah.com reference: Book 2, Hadith 349