Musar zu Bereschit 15:16

The spies commenced their report very deviously by referring to Amalek, whom they described as inhabiting the South of the land (13,29), thereby hinting at the role promised Joshua at the time he had led the battle against Amalek. What they meant to convey was that since Moses was alive and well, it was clear that the time to attempt to dislodge Amalek had not yet come, since that was to be Joshua's task only after Moses had died. Another reason they did so was that the very name of Amalek conjured up the time Israel had sinned when they had questioned G–d's presence in their midst, as a result of which Amalek had attacked them (see Rashi on Exodus 17,8). By mentioning Amalek they hinted that Israel was too enmeshed in sin to emerge victorious at this time from an encounter with Amalek. Concerning the Canaanites themselves the spies reported that they were אנשי מדות, i.e. people of considerable virtues, as we shall explain. Since G–d had told the people that the conquest of the land would not be on account of Israel's superior virtues, but on account of the inhabitants' moral inferiority, it was clear that the sin of the Emorite which was the precondition of successful battle against them had not yet reached the desired measure (comp. Genesis 15,16, and Deut. 9,5).