AN.1.56 is in Xuanzang’s Itivrttaka at T765.663c28, with prose and verse:
[0663c28] 吾從世尊聞如是語:「苾芻當知!世間所有惡不善法於生起時,諸不善品、諸不善類一切皆由意為前導。所以者何?意生起已,惡不善法皆隨後生。」爾時,世尊重攝此義而說頌曰:
I heard this from the Bhagavan: “Monks, you should know, when bad and unwholesome things arise in the world, all the sorts and kinds of unwholesome things have intention (mano) as their forerunner. Why is that? Intention has already arisen and bad and wholesome things arise afterwards.” Then the Bhagavan restated this in verse:
「諸不善法生, 為因能感苦,
皆意為前導, 與煩惱俱生;
Unwholesome things arise
To cause suffering;
They have intention as the forerunner,
And afflictions arise with them.
意為前導法, 意尊意所使。
由意有染污, 故有說有行,
Intention is the forerunning thing,
Intention is foremost, intention is what causes;
From mind, there is defilement,
So there is speech and action.
苦隨此而生, 如輪因手轉。」
Pain follows this and arises
Like a wheel is turned by the hand."
The next Iti sutra is the reverse, like the Dhammapada and AN.1.57.
So there’s the connection between the verse and the prose.
It’s interesting. I went looking for the gloss of unwholesome things in the Madhyama that I’d found. The reason I looked was when I was settling on my translation of the dhyana definitions. There’s the phrase “secluded from bad and unwholesome things.” Is it things or qualities? Well, in MA.68, which is the Sarvastivada version of DN.17, there’s a gloss of what those bad things are (which is not in the Pali):
[~517c25]『我是最後邊,念欲、念恚、念害、鬪諍、相憎、諛諂、虛偽、欺誑、妄言,無量諸[惡不善之法是最後邊。』
“To the very last, I was mindful of desire, mindful of hate, mindful of harmfulness, argument, mutual dislike, flattery, fraud, deception, lying, and the measureless bad and unwholesome things to the very last.”
So, it refers to behaviors as well as mental states in the Madhyama. This would resolve the trouble of AN.1.56-57. Mind comes before these types of actions.