Incensing of the Crucifix and Altar

The Priest incenses the crucifix and altar while reciting Psalm 140, 2-4:

DIRIGATUR, Domine, oratio mea, sicut incensum, in conspectu tuo:  elevatio manuum mearum sacrificium vespertinum.  Pone, Domine, custodiam ori meo, et ostium circumstantiae labiis meis: ut non declinet cor meum in verbo malitiae, ad excusandas excusationes in peccatis.

LET my prayer, O Lord, be directed as incense in Thy sight: the lifting up of my hands as an evening sacrifice.  Set a watch, O Lord, before my mouth, and a door round about my lips:  That my heart may not incline to evil words, and seek excuses in sins.