The emperor Justinian I was a formidable leader in 6th-century Byzantium. Among his many achievements is a legal code that would influence medieval law for generations. Here are some quotes from The Code of Justinian, and some that have been attributed to him.
The Code of Justinian
"Those things which seem to many former Emperors to require correction, but which none of them ventured to carry into effect, We have decided to accomplish at the present time with the assistance of Almighty God; and to diminish litigation by the revision of the multitude of constitutions which are contained in the Three Codes; namely, the Gregorian, the Hermogenian, and the Theodosian, as well as in those other Codes promulgated after them by Theodosius of Divine Memory, and by other Emperors, who succeeded him, in addition to those which We Ourselves have promulgated, and to combine them in a single Code, under Our auspicious name, in which compilation should be included not only the constitutions of the three above-mentioned Codes, but also such new ones as subsequently have been promulgated." - The First Preface
"The maintenance of the integrity of the government depends upon two things, namely, the force of arms and the observance of the laws: and, for this reason, the fortunate race of the Romans obtained power and precedence over all other nations in former times, and will do so forever, if God should be propitious; since each of these has ever required the aid of the other, for, as military affairs are rendered secure by the laws, so also are the laws preserved by force of arms." - The Second Preface
"For true and pious reasons, We direct that no one shall be permitted to remove from the holy churches persons who take refuge there, with the understanding that if anyone attempts to violate this law, he shall be considered guilty of the crime of treason." - TITLE XII
"If (as you allege), you, a minor of twenty years of age, have manumitted your slave, although you may have been fraudulently persuaded to do so, still, the imposition of the rod by which freedom is lawfully bestowed cannot be rescinded under the pretext of defect of age; the manumitted slave, however, must indemnify you, and this should be provided for by the magistrate having jurisdiction of the case to the extent that the law permits." - TITLE XXXI
"It was in your husband's power, in a fit of anger, to change the provisions which he had made in his will with reference to his slaves, namely, that one of them should remain in perpetual servitude, and that the other should be sold in order to be taken away. Hence, if afterwards, his clemency should mitigate his anger (which, although it may not be proved by documentary evidence, still, nothing prevents its being established by other testimony, especially when the subsequent meritorious conduct of the said slave is such that the wrath of the master has been appeased), the arbitrator in the action in partition should comply with the last wishes of the deceased." - TITLE XXXVI
"It is customary to come to the relief of persons who have attained their majority, where divisions of property have been made through fraud or deceit, or unjustly, and not as the result of a decision in court, because in bona fide contracts whatever is established to have been done unjustly shall be corrected." - TITLE XXXVIII
"Justice is the constant and perpetual wish to render to every one his due." - Institutiones, Book I
Quotes That Have Been Attributed to Justinian
"Frugality is the mother of all virtues."
"Glory to God who has thought me worthy to finish this work. Solomon, I have outdone you."
"Keep cool and you will command everyone."
"Rather let the crime of the guilty go unpunished than condemn the innocent."
"Safety of the state is the highest law."
"The things which are common to all (and not capable of being owned) are: the air, running water, the sea and the seashores."