Leading off the fourth chapter of Avot is the following (Avot 4.1):
בן זומא אומר:
איזה הוא חכם?
הלמד מכל אדם, שנאמר “מכל מלמדיי השכלתי”.
איזה הוא גיבור?
הכובש את יצרו, שנאמר “טוב ארך אפיים מגיבור”.
איזה הוא עשיר?
השמח בחלקו, שנאמר “יגיע כפיך, כי תאכל; אשריך, וטוב לך”.
איזה הוא מכובד?
המכבד את הברייות, שנאמר “כי מכבדיי אכבד ובוזיי ייקלו”.
[Simon] son of Zoma says:
Who is a sage?
One who learns from every person, as it is said, “I have become wisened from all of my teachers.”
Who is a strong man?
One who conquers his desire, as it is said, “Better to be slow to anger than mighty.”
Who is a rich man?
One who rejoices in his portion, as it is said, “You shall enjoy the fruit of your labors; you shall be happy and it will be good for you.”
Who is an honored man?
One who honors people, as it is said, “For I will honor those who honor me and I those who dishonor me will be spurned.”
In each of these four lines, there is a question “Who is [a particular descriptor]?” followed by a 2-3-word answer, followed by a Scriptural proof (“as it is said [scriptural verse]”).
Many printed versions of the text of this collection of statements of Simon, son of Zoma, include this line following the third statement:
“אשריך”, בעולם הזה; “וטוב לך”, לעולם הבא
“’You shall be fortunate’ – in this world, ‘and it will be good for you’ – in the world to come.”
However, this line expounding Psalms 128.2 is not part of Simon, son of Zoma’s statement, but was appended later on. This curious expounding might not be out of place for Ben Zoma, as he also did this just as Rabbi Elazar, son of Azariah, quoted him as expounding (mBer1.5 & tBer 1.10). Furthermore, it could have added a special dimension to his overall statements providing further flavor to them, yet, there are a few problems with this line actually being a part of the original statement.
The first problem with this extra line of expounding is that it is not found in the parallel text in Avot deRabbi Natan, where we might expect it to be found, as well.
The second problem is that this line is not essential to his message and, in fact, takes away from the rhetorical power of the rest of the line (and the other statements).
A third problem is that it does not fit with the larger pattern of the rest of his statements. This lack of fitting-in is the extra expounding on the verse, splitting it up it into two different topics, relating one to this world and the latter into the world to come, since none of the three other statements in this collection do such an action.
So whence did it come? It would seem that the first time this expounding of this verse is stated by Rav Zevid (Hullin 44b):
רב זביד אמר זוכה ונוחל שני עולמות העולם הזה והעולם הבא אשריך בעולם הזה וטוב לך לעולם הבא
Rav Zevid said: “He merits and inherits two worlds: this world and the world to come; ‘you are fortunate’ – in this world; ‘and it shall be good for you’ – in the world to come.”
Without the expounding of this verse, Rav Zevid’s statement would have no legs upon which to stand, as it forms the basis for his assertion.
Another appearance of the phrasing of this expounding of the verse occurs within a statement of Ulla’s as indirectly quoted by Rabbi Hiyya, son of Ammi (Berakhot 8a):
אמר רבי חייא בר אמי משמיה דעולא גדול הנהנה מיגיעו יותר מירא שמים.
דאילו גבי ירא שמים כתיב ‘אשרי איש ירא את ה”
ואילו גבי נהנה מיגיעו כתיב ‘יגיע כפיך כי תאכל אשריך וטוב לך’
אשריך בעולם הזה וטוב לך לעולם הבא
ולגבי ירא שמים וטוב לך לא כתיב ביה
Rabbi Hiyya, son of Ammi, said, from the name of Ulla: “Better is one who benefits from his toil than one who is in awe of Heaven.
For, with regard to the one who fears heaven, it is written: ‘Happy is the man that fears the Lord.’
While with regard to the man who lives from his own work it is written: ‘When you eat the labor of your hands, you will be happy, and it shall be well with you.’”
“You will be fortunate” – in this world, “and it shall be well with you” – in the world to come.
But, of the man that fears heaven, it is not written: “and it shall be well with you.”
After the assertion that one who benefits from his toil is better than one who is in awe of Heaven, Ps. 112.1 is trotted out regarding first the one who fears Heaven, followed by one who benefits from his work, utilizing Ps. 128.2, then the expounding of Ps. 128.2, followed by the pointing out of what differentiates Ps. 112.1 from Ps. 128.2. While the expounding of Ps. 128.2 is neat, it has nothing to do with the argument being made differentiating the two verses. In fact, the text reads more cleanly by removing the line of “אשריך בעולם הזה וטוב לך לעולם הבא”.
And not only has it been added in just the previous text, it also happened to Simon, son of Zoma’s statements in Avot 4:1, as well as in Avot 6.4. It may be that because people got familiar with repeating it for Rav Zevid’s statement, it was reflexively appended to the other statements which utilized this verse.
 Although not all printed versions include this line; see Shimon Sharvit, מסכת אבות לדורותיה: מהדורה מדעית, מבואות ונספחים (Jerusalem: Bialik Institute, 2004), 148.
 See also Mekhilta, Bo, Parshah 16. Regarding that expounding, although that, too, may seem strange, “obviously, the ‘logic’ of the reading is in Ben Zoma’s fertile imagination. To a casual contemporary reader, this text seems peculiar indeed. But once we recognize the particular style of close reading and the typical playfulness of the midrashic mind, the…text makes perfect sense.” (Barry W. Holtz, “Midrash,” in Back to the Sources: Reading the Classic Jewish Texts, ed. Barry W. Holtz (New York: Simon & Schuster, 1984), 203.)
 For instance,
Ben Zoma’s interpretation of the verse from Psalms adds another dimension to his maxim, by placing it in the context of a wider religious outlook. In a characteristic midrashic commentary, he attributes different intent and meaning to the poetical duplication of the verse. While the statements “happy shalt thou be” and “it shall be well with thee” are intended by the Psalmist as no more than the repetition of the same idea, Ben Zoma uses them to convey two different, though complementary, propositions. “Happy shalt thou be” is addressed to life in this world, comments the tanna, while “it shall be well with thee” conveys the promise of wellbeing in the world to come.
By relating the maxim of moderation in the quest for riches to the award of happiness in the world to come, Ben Zoma elevates the dictum to a new high level. It is no more only psychological advice with social implications; it becomes a maxim involving an absolute dimension, for it is related not merely to terrestrial affairs of a transient nature, at least as far as the virtuous individual is concerned. It touches the continuing, endless, immortal condition of the said individual, it verges on the absolute. The person who is happy with what he has, and does not devote his life to a never-ending quest for riches, is not only a happier person; he is also a better person as judged by an absolute scale of values. (Mordecai Roshwald, “The Teaching of Ben Zoma,” Judaism 42, 1 (Winter 1993), 22.)
 Wilhelm Bacher, Die Agada der Tannaiten (Strasburg: Karl J. Trübner, 1903), 427, n. 5.
 Sticking out like a sore thumb caught my attention and made me realize that this line did not fit within the rest of the overall statement.