I had hardly thought by asking
For five hundred I’d be tasking
The kindness of a rich old friend like you.
“Practice law,” you said, “it’s healthy,
And it soon will make you wealthy.”
Now, Gaius, tell me “Yes,” not what to do.

[Mutua viginti sestertia forte rogabam,
Quae vel donanti non grave munus erat.
Quippe rogabatur felixque vetusque sodalis
Et cuius laxas arca flagellat opes.
Is mihi ‘Dives eris, si causas egeris’ inquit.
Quod peto da, Gai: non peto consilium.]

Martial (AD c.39-c.103) Spanish Roman poet, satirist, epigrammatist [Marcus Valerius Martialis]

Epigrams [Epigrammata], Book 2, epigram 30 (2.30) (AD 86) [tr. Nixon (1911), “Neither a Borrower”]
    (Source)

"To Caius/Gaius." (Source (Latin)). Alternate translations:

When twenty pounds I'd borrow of a friend,
One, who might give me more, as well as lend;
Blest in his fortune; my companion old;
Whose coffers, and whose purse-strings, crack with gold.
"Turn lawyer, and you'll soon grow rich," he cries:
Give me what I ask, my friend: -- 'tis not advice.
[tr. Hay (1755)]

Of sesterces a score I crave in loan,
Which scarce a boon would honest bounty own.
A fortune-blest old intimate I urge,
Whose gen'rous wealth tyrannic coffers scourge.
"Go, ply the bar: be affluent in a trice."
I ask your aid, my Cay, not your advice.
[tr. Elphinston (1782), Book 5, ep. 31]

I asked Caius to lend me twenty sestertia, a sum which could not weigh heavy on him, even if he had been asked to give and not to lend; for he was my old companion, and hd been fortunate in life; and his chest can scarcely press down his overflowing riches. He replied to me, "You will become wealthy if you will take to pleading causes." Caius! give me what I ask for, I do not ask for advice.
[tr. Amos (1858), "Unseasonable Advice"; ch. 3, ep. 89]

I asked, by chance, a loan of twenty thousand sesterces, which would have been no serious matter even as a present. He whom I asked was an old acquaintance in good circumstances, whose money-chest finds difficulty in imprisoning his overflowing hoards. "You will enrich yourself, was his reply, "if you will go to the bar." Give me, Caius, what I ask: I do not ask advice.
[tr. Bohn's Classical (1859)]

I asked, as it chanced, the loan of twenty thousand sesterces, which, even to a give, would have been no burden. The fact was I asked them of a well-to-do and old friend, and one whose money-chest keeps in control o'erflowing wealth. His answer was, "You will be rich if you plead causes." Give me what I ask, Gaius: I don't ask for advice.
[tr. Ker (1919)]

I chanced to ask a loan -- a hundred, merely;
E'en as a gift that should not task severely
A wealthy friend, and so I asked him, knowing
His pockets bulge with cash over-flowing.
"Go to the Bar," says he, "get rich by pleading" --
'Tis cash, not counsel, Gaius, that I'm needing.
[tr. Pott & Wright (1921)]

I asked you twenty thousand as a loan,
A trifle, had I craved it for my own,
Such claim might ancient friendship well afford
On one whose coffers chid their bursting hoard.
"Plead and you'll make a fortune in a trice."
I want your money, Gaius, not advice.
[tr. Francis & Tatum (1924), ep. 79]

I asked a rich old friend of mine
for a loan of twenty thousand:
No trouble at all for him to give it to me,
he was so loaded. But in answer to my request
he said, "You know what? You want to make money?
Become a lawyer." Look, Gaius:
I asked you for money, not for advice.
[tr. Bovie (1970)]

I happened to ask a Ioan of twenty thousand sesterces, no burdensome present even as a gift. He of whom I asked it was a faithful old friend, he whose coffer whips up his ample wealth. Says he to me: "You'll be a rich man if you plead cases." Give me what I ask, Gaius; I'm not asking advice.
[tr. Shackleton Bailey (1993)]

I need a loan of twenty grand.
Can you lend a helping hand?
We're friends, it's not a huge amount
Against your massive bank account.
But your reply? "Go practice law,
it's easy to get rich, ha-ha!"
So here's a thought on which to chew:
No job advice I asked from you.
[tr. Ericsson (1995)]

I chanced to seek a loan of twenty thousand --
which one could give away and not think twice.
The man I asked, a trusted longtime friend,
whose strongbox whips up riches in a trice,
said, "Be a lawyer. You'll make piles of cash."
I asked for money, Gaius, not advice.
[tr. McLean (2014)]