Nicene and Post-Nicene Fathers, Ser. II, Vol. XIV:
The Canons of the Councils of Ancyra, Gangra, Neocæsarea, Antioch and Laodicea, which Canons were Accepted and Received by the Ecumenical Synods.: Canon XLVII

Canon XLVII.

They who are baptized in sickness and afterwards recover, must learn the Creed by heart and know that the Divine gifts have been vouchsafed them.

Notes.

Ancient Epitome of Canons XLVI. and XLVII.

Whoso is baptised by a bishop or presbyter let him recite the faith on the fifth feria of the week.  Also anyone baptized clinically a short while afterwards.

Balsamon.

Some unbelievers were baptized before they had been catechized, by reason of the urgency of the illness.  Now some thought that as their baptism did not follow their being catechumens, they ought to be catechized and baptized over again.  And in support of this opinion they urged Canon XII. of Neocæsarea, which does not permit one clinically baptized to become a priest rashly.  For this reason it is that the Fathers decree that such an one shall not be baptized a second time, but as soon as he gets well he shall learn the faith and the mystery of baptism, and to appreciate the divine gifts he has received, viz., the confession of the one true God and the remission of sins which comes to us in holy baptism.