That’s a toughie.
I hate to answer a question with a question, but please bear with me. Do you believe in the Trinity? I’m assuming that you do.
Where does the Bible say that there is a Trinity?
Plain and simple, it doesn’t. The Teaching is taught explicitly in Sacred Tradition and is only implied in the Bible.
The same here. The Catholic Church explicitly teaches that the Saints can hear our prayers. But this Teaching is only implied in the Bible.
However, the question reveals a false assumption on the part of the people asking the question.
They assume that Jesus wrote a Bible and handed it out. Or that the Apostles wrote the New Testament before they began to preach. But that is false.
The fact is that Jesus established the Church. He then commissioned the Church to Teach all which He commanded.
It is based upon these Teachings that the Catholic Church wrote the New Testament.
Ok, so, where does the Bible imply that people in heaven can hear our prayers?
One of my favorite places is this one. It doesn’t depict someone from heaven, but it does depict “dead people” having a lively conversation.
Luke 16:27 Then he said, I pray thee therefore, father, that thou wouldest send him to my father’s house: 28 For I have five brethren; that he may testify unto them, lest they also come into this place of torment. 29 Abraham saith unto him, They have Moses and the prophets; let them hear them.
30 And he said, Nay, father Abraham: but if one went unto them from the dead, they will repent.
31 And he said unto him, If they hear not Moses and the prophets, neither will they be persuaded, though one rose from the dead.
That is Jesus depicting a DEAD MAN speaking to Abraham about Lazarus.
All of whom are dead. If you remember, Jesus did not say that this was a parable. He said, “19 There was a certain rich man….” That means that Jesus is narrating a true story.
This story reveals many things.
1. Dead men, in hell (v 23, an in hell he lift up his eyes….), can speak.
2. Dead men, in hell, can see what is going on, on earth.
3. Dead men, in hell, can pray for intercession on behalf of their brothers.
4. Dead men hell are under the impression that dead men in purgatory (i.e. the Bosom of Abraham) are fully capable of going into men’s houses and testifying (v. 27).
5. Finally, the story also reveals that dead men who are not in hell (Abraham and Lazarus) and not even in heaven, yet, are seemingly, very much alive, self aware and aware of things upon earth.
Before the Holy Spirit was given
So, if dead men in hell and dead men who were not in hell, but not yet in heaven, could do so much talking and living before the Crucifixion. Before the Holy Spirit was given. How much more afterwards?
Is there any place where the Bible implies that people in heaven can hear our prayers?
Revelation 5:8 And when he had taken the book, the four beasts and four and twenty elders fell down before the Lamb, having every one of them harps, and golden vials full of odours, which are the prayers of saints.
I don’t know what the “beasts” represent. I assume, angels. But the four and twenty elders are saints in heaven. And everyone of them has the prayers of the saints from earth.
I hope that helps. Thanks for listening.