Matthew 7:6
4 Or how can you say to your brother, ‘Let me remove the speck from your eye,’ while there is a beam in your own? 5 You hypocrite! First remove the beam from your own eye, and then you can see clearly to remove the speck from your brother’s eye. 6 Do not give what is holy to dogs or throw your pearls before pigs; otherwise they will trample them under their feet and turn around and tear you to pieces. 7 “Ask and it will be given to you; seek and you will find; knock and the door will be opened for you. 8 For everyone who asks receives, and the one who seeks finds, and to the one who knocks, the door will be opened.
Didache 9:5
3 Concerning the broken Bread, say: 'We thank You, our Father, for the life and knowledge that You revealed to us through Jesus Your Son. May You be glorified forever.' 4 Just as this broken bread was scattered over the hills and then gathered together and became one, so let Your Church be gathered together from the ends of the earth into Your kingdom. Yours is the glory and power through Jesus Christ forever.' 5 Only those who have been baptized in the Lord's Name may eat or drink of your Eucharist. For the Lord also said, 'Do not give what is holy to dogs.'
Notes and References
"... a requirement of secrecy is a common feature of ritual initiations or temple ordinances. Indeed, Didache 9:5 associates this saying in Matthew 7:6 with a requirement of cultic exclusivity, specifically the prohibition not to let anyone “eat or drink of the Eucharist with you except for those baptized in the name of the Lord” (see Didache 14:1–2, also connecting the gift at the altar in Matthew 5:23–5 with the observance of the Eucharist). Accordingly, Betz concludes that “the ‘holy’ could be a ritual.” In any event, when the body of sacred knowledge is given by the Sermon on the Mount to its recipients, its elements become or produce a string of precious pearls of great price, “your pearls,” which are revelations that one would sell all that one has in order to obtain (see Matthew 13:45–6). Once that knowledge is found, one keeps it hidden to protect it (see Matthew 13:44). The violation of this obligation of secrecy carries or implies harsh penalties and consequences. If it is violated, the pearls will be trampled, and the one who has disclosed the holy thing will be torn to pieces ..."
Welch, John W. The Sermon on the Mount in the Light of the Temple (p. 169) Ashgate, 2009