It is narrated from Sayyiduna Abu Hurayrah (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "When you load baggage, do it last, for the hands hang loose and the feet are firm."
Al-Zuhri (may Allah have mercy on him) reports a narration from the Prophet (peace and blessings be upon him): "Load the baggage onto the mounts last, for the hands hang loose and the feet are firm."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الإجارة / 11663