1. pra 2. sam 3. u and 4. ut are repeated when by so doubling, the foot of a verse is completed.,
As प्र प्रायमग्निभरतस्य शृण्वे (Rig VII. 8. 4), संसमिद्युवते वृषन् ॥ (Rig X. 191. 1), उपोप मे परामृश (Rig I. 126. 7), किं नोदुदु हर्षसे दातवाउ (Rig IV. 21. 9). Why do we say when 'a foot of a verse is completed there by'? Observe प्रदेवं देव्या धिया ॥ This rule applies only to the Vedic verses, for there alone the Preposition may be used separate from its verb. In the secular literature, this rule has no applicability, as Prepositions are never so used.,