Genesis 5:25

25 When Methuselah had lived 187 years, he became the father of Lamech.

Read Genesis 5:25 Using Other Translations

And Methuselah lived an hundred eighty and seven years, and begat Lamech:
When Methuselah had lived 187 years, he fathered Lamech.
When Methuselah was 187 years old, he became the father of Lamech.