user24191: In many suttas, the Buddha affirms his omniscience about the past of all the beings.
Why didn't the Buddha say something about his omniscience about the future of all the beings, in suttas?

user471: The sutta below states that the Buddha doesn't know everything. He is not all-knowing, and not omniscient.
However, he does possess three knowledges for sure:

He could recollect his own past existences
He is able to see using his supernatural powers, how sentient beings have their existences ceased and renewed based on their karma
He is able to understand undefiled freedom of heart and freedom of wisdom, based on the ending of defilements.

There is no indication in the three knowledges above that he could definitely foresee the future states of all beings.

“Sir, I have heard this: ‘The ascetic Gotama claims to be all-knowing
and all-seeing, to know and see everything without exception, thus:
“Knowledge and vision are constantly and continually present to me,
while walking, standing, sleeping, and waking.”’ I trust that those
who say this repeat what the Buddha has said, and do not misrepresent
him with an untruth? Is their explanation in line with the teaching?
Are there any legitimate grounds for rebuke and criticism?”
“Vaccha, those who say this do not repeat what I have said. They
misrepresent me with what is false and untrue.”
“So how should we answer so as to repeat what the Buddha has said, and
not misrepresent him with an untruth? How should we explain in line
with his teaching, with no legitimate grounds for rebuke and
criticism?”
“‘The ascetic Gotama has the three knowledges.’ Answering like this
you would repeat what I have said, and not misrepresent me with an
untruth. You would explain in line with my teaching, and there would
be no legitimate grounds for rebuke and criticism.
For, Vaccha, whenever I want, I recollect my many kinds of past lives.
That is: one, two, three, four, five, ten, twenty, thirty, forty,
fifty, a hundred, a thousand, a hundred thousand rebirths; many eons
of the world contracting, many eons of the world expanding, many eons
of the world contracting and expanding. I remember: ‘There, I was
named this, my clan was that, I looked like this, and that was my
food. This was how I felt pleasure and pain, and that was how my life
ended. When I passed away from that place I was reborn somewhere else.
There, too, I was named this, my clan was that, I looked like this,
and that was my food. This was how I felt pleasure and pain, and that
was how my life ended. When I passed away from that place I was reborn
here.’ And so I recollect my many kinds of past lives, with features
and details.
And whenever I want, with clairvoyance that is purified and
superhuman, I see sentient beings passing away and being
reborn—inferior and superior, beautiful and ugly, in a good place or a
bad place. I understand how sentient beings are reborn according to
their deeds.
And I have realized the undefiled freedom of heart and freedom by
wisdom in this very life. I live having realized it with my own
insight due to the ending of defilements.
‘The ascetic Gotama has the three knowledges.’ Answering like this you
would repeat what I have said, and not misrepresent me with an
untruth. You would explain in line with my teaching, and there would
be no legitimate grounds for rebuke and criticism.”
MN 71


24191: <p>In many suttas, the Buddha affirms his omniscience about the past of all the beings.
Why didn't the Buddha say something about his omniscience about the future of all the beings, in suttas?</p>
 471: <p>The sutta below states that the Buddha doesn't know everything. He is not all-knowing, and not omniscient.</p>
<p>However, he does possess three knowledges for sure:</p>
<ul>
<li>He could recollect his own past existences</li>
<li>He is able to see using his supernatural powers, how sentient beings have their existences ceased and renewed based on their karma</li>
<li>He is able to understand undefiled freedom of heart and freedom of wisdom, based on the ending of defilements.</li>
</ul>
<p>There is no indication in the three knowledges above that he could definitely foresee the future states of all beings.</p>
<blockquote>
<p>“Sir, I have heard this: ‘The ascetic Gotama claims to be all-knowing
and all-seeing, to know and see everything without exception, thus:
“Knowledge and vision are constantly and continually present to me,
while walking, standing, sleeping, and waking.”’ I trust that those
who say this repeat what the Buddha has said, and do not misrepresent
him with an untruth? Is their explanation in line with the teaching?
Are there any legitimate grounds for rebuke and criticism?”</p>
<p>“Vaccha, those who say this do not repeat what I have said. They
misrepresent me with what is false and untrue.”</p>
<p>“So how should we answer so as to repeat what the Buddha has said, and
not misrepresent him with an untruth? How should we explain in line
with his teaching, with no legitimate grounds for rebuke and
criticism?”</p>
<p>“‘The ascetic Gotama has the three knowledges.’ Answering like this
you would repeat what I have said, and not misrepresent me with an
untruth. You would explain in line with my teaching, and there would
be no legitimate grounds for rebuke and criticism.</p>
<p>For, Vaccha, whenever I want, I recollect my many kinds of past lives.
That is: one, two, three, four, five, ten, twenty, thirty, forty,
fifty, a hundred, a thousand, a hundred thousand rebirths; many eons
of the world contracting, many eons of the world expanding, many eons
of the world contracting and expanding. I remember: ‘There, I was
named this, my clan was that, I looked like this, and that was my
food. This was how I felt pleasure and pain, and that was how my life
ended. When I passed away from that place I was reborn somewhere else.
There, too, I was named this, my clan was that, I looked like this,
and that was my food. This was how I felt pleasure and pain, and that
was how my life ended. When I passed away from that place I was reborn
here.’ And so I recollect my many kinds of past lives, with features
and details.</p>
<p>And whenever I want, with clairvoyance that is purified and
superhuman, I see sentient beings passing away and being
reborn—inferior and superior, beautiful and ugly, in a good place or a
bad place. I understand how sentient beings are reborn according to
their deeds.</p>
<p>And I have realized the undefiled freedom of heart and freedom by
wisdom in this very life. I live having realized it with my own
insight due to the ending of defilements.</p>
<p>‘The ascetic Gotama has the three knowledges.’ Answering like this you
would repeat what I have said, and not misrepresent me with an
untruth. You would explain in line with my teaching, and there would
be no legitimate grounds for rebuke and criticism.”<br />
<a href="https://suttacentral.net/mn71/en/sujato" rel="nofollow noreferrer">MN 71</a></p>
</blockquote>
