Theodoret relates the words of Athanasius:
"The followers of Eusebius were covered with shame, and buried him whose belief they shared. The blessed Alexander completed the celebration, rejoicing with the Church in piety and orthodoxy, praying with all the brethren and greatly glorifying God. This was not because he rejoiced at the death of Arius—God forbid; for 'it is appointed unto all men once to die'; but because the event plainly transcended any human condemnation. For the Lord Himself passing judgment upon the menaces of the followers of Eusebius, and the prayer of Alexander, condemned the Arian heresy, and shewed that it was unworthy of being received into the communion of the Church; thus manifesting to all that, even if it received the countenance and support of the emperor, and of all men, yet by truth itself it stood condemned."
See The Ecclesiastical History of Theodoret (Book 1, Extract from the Letter of Athanasius on the Death of Arius)