MN62 Maha-Rahulovada Sutta is one of them.
"[1] Breathing in long, he discerns, 'I am breathing in long'; or
breathing out long, he discerns, 'I am breathing out long.' [2] Or
breathing in short, he discerns, 'I am breathing in short'; or
breathing out short, he discerns, 'I am breathing out short.' [3] He
trains himself, 'I will breathe in sensitive to the entire body.' He
trains himself, 'I will breathe out sensitive to the entire body.' [4]
He trains himself, 'I will breathe in calming bodily fabrication.' He
trains himself, 'I will breathe out calming bodily fabrication.'
"[5] He trains himself, 'I will breathe in sensitive to rapture.' He
trains himself, 'I will breathe out sensitive to rapture.' [6] He
trains himself, 'I will breathe in sensitive to pleasure.' He trains
himself, 'I will breathe out sensitive to pleasure.' [7] He trains
himself, 'I will breathe in sensitive to mental fabrication.' He
trains himself, 'I will breathe out sensitive to mental fabrication.'
[8] He trains himself, 'I will breathe in calming mental fabrication.'
He trains himself, 'I will breathe out calming mental fabrication.'
"[9] He trains himself, 'I will breathe in sensitive to the mind.' He
trains himself, 'I will breathe out sensitive to the mind.' [10] He
trains himself, 'I will breathe in satisfying the mind.' He trains
himself, 'I will breathe out satisfying the mind.' [11] He trains
himself, 'I will breathe in steadying the mind.' He trains himself, 'I
will breathe out steadying the mind.' [12] He trains himself, 'I will
breathe in releasing the mind.' He trains himself, 'I will breathe out
releasing the mind.'
"[13] He trains himself, 'I will breathe in focusing on inconstancy.'
He trains himself, 'I will breathe out focusing on inconstancy.' [14]
He trains himself, 'I will breathe in focusing on dispassion.'[5] He
trains himself, 'I will breathe out focusing on dispassion.' [15] He
trains himself, 'I will breathe in focusing on cessation.' He trains
himself, 'I will breathe out focusing on cessation.' [16] He trains
himself, 'I will breathe in focusing on relinquishment.' He trains
himself, 'I will breathe out focusing on relinquishment.'
"This, Rahula, is how mindfulness of in-&-out breathing is developed &
pursued so as to be of great fruit, of great benefit.
"When mindfulness of in-&-out breathing is developed & pursued in this
way, even one's final in-breaths & out-breaths are known as they
cease, not unknown."[6]
Just as the what was instructed by Buddha to Ven Rahula. This is the only way that i understand and experienced it myself.