Hi Truth_Teller,
Young's Literal Translation renders the verse this way:
And he said to them, `Because of this every scribe having been discipled in regard to the reign of the heavens, is like to a man, a householder, who doth bring forth out of his treasure things new and old.'
In the Orthodox Jewish Bible, (youversion.com) and the Hebrew phrase for 'householder' means 'Master of the house'.
It brings to mind these verses at the beginning of Hebrews 3:
1 Wherefore, holy brethren, partakers of the heavenly calling, consider the Apostle and High Priest of our profession, Christ Jesus; 2 Who was faithful to him that appointed him, as also Moses [was faithful] in all his house.
3 For this [man] was counted worthy of more glory than Moses, inasmuch as he who hath builded the house hath more honour than the house. 4 For every house is builded by some [man]; but he that built all things [is] God. 5 And Moses verily [was] faithful in all his house, as a servant, for a testimony of those things which were to be spoken after; 6 But Christ as a son over his own house; whose house are we, if we hold fast the confidence and the rejoicing of the hope firm unto the end.
John 15:15 Henceforth I call you not servants; for the servant knoweth not what his lord doeth: but I have called you friends; for all things that I have heard of my Father I have made known unto you.
John 3:10 Jesus answered and said unto him, Art thou a master of Israel, and knowest not these things? 11 Verily, verily, I say unto thee, We speak that we do know, and testify that we have seen; and ye receive not our witness. 12 If I have told you earthly things, and ye believe not, how shall ye believe, if I tell you [of] heavenly things?
The way I'm adding this all together is, Jesus was indicating that to become a 'Master', the scribe - the disciple (not teacher) - of the kingdom of heaven - must be fully conversant with the new revelation (the gospel of Jesus Christ) as well as the preceding one (the Old Covenant).
This understanding (of both) is his 'treasure'. Some of it is old treasure. Some of it is new treasure. Depending on the need of the moment, he can call upon this 'treasure' to sustain him - and those entrusted to him - to build them up in the knowledge of God and His faithfulness. (I say His faithfulness, because this is proven by the coming of the Messiah in answer to so many prophesies, and then by His faithful ministry in obedience to His Father. This knowledge is treasure, too.)