Today's WT Study, from the December 15, 2014, is based on Mark 7:14, which says:
So calling the crowd to him again, he said to them: “Listen to me, all of you, and understand the meaning.
The two words at the end, "the meaning", are not found in the Greek. The statement should read: "Listen to me, all of you, and understand."
Also, this is another example of cherry-picking a verse and pulling it out of context, using it to apply to something else entirely. The original context is this (Mark 7:1-15):
Now the Pharisees and some of the scribes who had come from Jerusalem gathered around him. 2 And they saw some of his disciples eat their meal with defiled hands, that is, unwashed ones. 3 (For the Pharisees and all the Jews do not eat unless they wash their hands up to the elbow, clinging to the tradition of the men of former times, 4 and when they come from the market, they do not eat unless they wash themselves. There are many other traditions that they have received and cling to, such as baptisms of cups, pitchers, and copper vessels.) 5 So these Pharisees and scribes asked him: “Why do your disciples not observe the tradition of the men of former times, but they eat their meal with defiled hands?” 6 He said to them: “Isaiah aptly prophesied about you hypocrites, as it is written, ‘This people honor me with their lips, but their hearts are far removed from me. 7 It is in vain that they keep worshipping me, for they teach commands of men as doctrines.’ 8 You let go of the commandment of God and cling to the tradition of men.”
9 Further, he said to them: “You skillfully disregard the commandment of God in order to keep your tradition. 10 For example, Moses said, ‘Honor your father and your mother,’ and, ‘Let the one who speaks abusively of his father or mother be put to death.’ 11 But you say, ‘If a man says to his father or his mother: “Whatever I have that could benefit you is corban (that is, a gift dedicated to God),”’ 12 you no longer let him do a single thing for his father or his mother. 13 Thus you make the word of God invalid by your tradition that you have handed down. And you do many things like this.” 14 So calling the crowd to him again, he said to them: “Listen to me, all of you, and understand the meaning. 15 Nothing from outside a man that enters into him can defile him; but the things that come out of a man are the things that defile him.”