Grail Psalter: "Today, listen to the voice of the Lord."
New American Bible (Revised Edition): "Oh, that today you would hear his voice"
Douay Rheims: "To day if you shall hear his voice"
American Standard Version: "To-day, oh that ye would hear his voice!"
Complete Jewish Bible: "If only today you would listen to his voice."
Geneva: "today, if ye will hear his voice"
King James Version: "To day if ye will hear his voice"
Orthodox Jewish Bible: "Today if ye will hear His voice"
Revised Standard Version Catholic Edition: "O that today you would hearken to his voice!"
Young's Literal Translation: "To-day, if to His voice ye hearken"
The point being:
The "if" is not on God's part. God is speaking to you. Today.
The "if" is on your part -- and my part, and everyone's part, every day since Adam and Eve hid themselves when God called to them in the Garden.