Beyond their power (para dunamin). “Alongside” with accusative like huper dunamin in 2Co 1:8. Field (Ot. Nov.) quotes Josephus (Ant. iii. 6, 1) for kata dunamin and para dunamin as here. Few give kata dunamin (according to actual ability). Paul commends this high pressure collection because of the emergency.
Of their own accord (authairetoi). Old verbal adjective (autos, hairetos from haireomai, to choose), of their own initiative, voluntary. Only here and 2Co 8:17 in N.T. Papyri often have hekousiōs kai authairetōs (willingly and voluntarily).