Redemption Paladins get an “Aura of the Guardian” :
Starting at 7th level, you can shield others from harm at the cost of your own health. When a creature within 10 feet of you takes damage, you can use your reaction to magically take that damage, instead of that creature taking it. This feature doesn't transfer any other effects that might accompany the damage, and this damage can't be reduced in any way.
The Berserker Axe comes with a curse:
Whenever a hostile creature damages you while the axe is in your possession, you must succeed on a DC 15 Wisdom saving throw or go berserk.
Now, say that Robert the Redemption Paladin is close to Fred the Fighter, who receives an arrow from Gabby the Hostile Goblin. Robert decides to use his reaction to absorb the damage that Fred would take. But! Robert is attuned to a berserker axe. Must Robert make the berserk saving throw?
In more general terms: Does absorbing damage from an ally hurt by a hostile creature counts as being (indirectly) hurt by the hostile creature?