Charles Ellicott Commentary Matthew 6:34

"Be not therefore anxious for the morrow: for the morrow will be anxious for itself. Sufficient unto the day is the evil thereof." — Matthew 6:34 (ASV)

Take therefore no thought for the morrow — No precept of divine wisdom has found so many echoes in the wisdom of the world. Epicurean self-indulgence, Stoic apathy, and practical common sense have all preached the same lesson and urged men to cease their questioning about the future. What was new in our Lord’s teaching was the ground on which the precept rested. It was not simply the carpe diem—“make the most of the present”—of the seeker after a maximum of enjoyment, nor the acceptance by man’s will of an inevitable destiny, nor the vain struggle to rise above that inevitable fate. Men were to look forward to the future calmly, to avoid the temperament that is
“Over-exquisite
To cast the fashion of uncertain evils,”
because they had a Father in heaven who cared for each one of them with a personal and individual love.

Sufficient unto the day is the evil thereof — The word translated as “evil” occurs in the Gospels only in this passage, and in the Epistles commonly has the sense of “wickedness.” That meaning would be too strong here, but it reminds us that our Lord is speaking not of what we call the simple accidents or misfortunes of life, but of the troubling element that each day brings with it, and against which we must contend, lest it lead us into sin. That conflict is more than enough for the day, without anticipating further trouble.