Lying and Laying

Don't mix up lie and lay. You lay something as in:

They are going to lay the carpet.

But you lie down on a bed or other flat surface.

Sentences such as the following ones are wrong.

He is laying on the bed or why don't you lie it on the bed?

Correct forms are:

He is lying on the bed and why don't you lay it on the bed?

The past tense and past participle of lay is laid.

They laid the groundwork.

She had laid careful plans.

The past tense of lie is lay and the past participle is lain.

He lay on the floor.

She had lain on the bed for hours.

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"Nay! man is evidence against himself. Though he puts forth his excuses." Holy Qur'an (75:14-15)