Jesus says in Matthew 6:34: "Therefore do not worry about tomorrow, for tomorrow will worry about its own things. Sufficient for the day is its own trouble."
Proverbs 27:1 says "Do not boast about tomorrow, for you do not know what a day may bring forth."
James 4:13-17 says "Come now, you who say, 'Today or tomorrow we will go into this city, spend a year there, buy and sell, and make a profit,' whereas you do not know what will happen tomorrow. What is your life? It is just a vapor that appears for a little while and then vanishes away. Instead you ought to say, “If the Lord wills, we shall live and do this or that.” But now you are rejoicing in your boastings. All such rejoicing is evil. Therefore, to him who knows to do good and does not do it, it is sin."