"But Daniel purposed in his heart that he would not defile himself with the portion of the king's meat, nor with the wine which he drank: therefore he requested of the prince of the eunuchs that he might not defile himself." Daniel 1:8
In this verse it says that Daniel purposed in his heart not to do something. What did Daniel purpose "not" to do? He purposed not to "defile himself". What did he consider to be an act that would defile him? Daniel's life was governed by the laws of God. God's laws included dietary laws- there were certain foods they were allowed to eat and others that they were commanded not to eat.
In the king's palace Daniel was presented with a meal that according to the law of God he wasn't allowed to eat. This was why Daniel did not want to defile himself. You may wonder why it was such a big issue to Daniel. It was just a plate of food. He wasn't asked to blaspheme the Lord. He wasn't asked to make a sacrifice to an idol. He wasn't asked to denounce the Lord God and worship a false god. He wasn't asked to do something which we consider "big"; it was a "small" thing. How could eating a little meat and drinking a cup of wine be considered "defiling himself"?
True, eating this certain food may not have been considered as big an offense like blaspheme, etc., but it was still in disobedience to the commands and laws of God. Daniel knew that all disobedience was sin and sin would defile you- even sins that seemed small and insignificant.
It may seem "silly" to us that Daniel made such a big deal out of a plate of food, but he knew that if he ate that plate of food he would be disobeying God. He knew that by eating, his disobedience would be sin. He knew sin will always defile you- it will always leave a "stain". The issue for Daniel was not the food, the issue was his obedience to God. Therefore, he took God's laws and commandments serious-- even the ones that might be considered "small" issues.
How do you see God's commandments? Do you categorize them-- big and small; significant and insignificant; important and not important? Do you pick and choose which ones you think won't matter if you break them and which ones will? All of God's laws are important and He expects you to obey all of them, regardless of how you might classify them. (There are no big sins and little sins- they will all "defile" you.)
Have a great day. Keeping God's commandments is a big deal and we need to take keeping ALL of them more seriously.
For further reading:
Deuteronomy 11:32; 28:58